Memory usage of prometheus is very high

We are using Prometheus as the monitoring component in our Kubernetes cluster to observe incoming requests to our pods and assist in autoscaling when requests exceed the predefined threshold. For Prometheus to scrape request metrics, we annotate the pods as needed. However, even after removing certain annotations, we are not seeing a significant reduction in memory usage—only a minimal decrease.
Below, I’ve included our current Prometheus configuration for review. Each pod contains an istio-proxy sidecar container alongside the main application container. We are using Prometheus specifically to track requests hitting the pods via istio-proxy. Could you please help us identify any configuration changes or optimizations to further reduce memory consumption?

  prometheus.yml: |
    global:
      evaluation_interval: 1m
      scrape_interval: 15s
      scrape_timeout: 10s
    rule_files:
    - /etc/config/recording_rules.yml
    - /etc/config/alerting_rules.yml
    - /etc/config/rules
    - /etc/config/alerts
    scrape_configs:
    - job_name: prometheus
      static_configs:
      - targets:
        - localhost:9090
    - bearer_token_file: /var/run/secrets/kubernetes.io/serviceaccount/token
      job_name: kubernetes-apiservers
      kubernetes_sd_configs:
      - role: endpoints
      relabel_configs:
      - action: keep
        regex: default;kubernetes;https
        source_labels:
        - __meta_kubernetes_namespace
        - __meta_kubernetes_service_name
        - __meta_kubernetes_endpoint_port_name
      scheme: https
      tls_config:
        ca_file: /var/run/secrets/kubernetes.io/serviceaccount/ca.crt
        insecure_skip_verify: true
    - bearer_token_file: /var/run/secrets/kubernetes.io/serviceaccount/token
      job_name: kubernetes-nodes
      kubernetes_sd_configs:
      - role: node
      relabel_configs:
      - action: labelmap
        regex: __meta_kubernetes_node_label_(.+)
      - replacement: kubernetes.default.svc:443
        target_label: __address__
      - regex: (.+)
        replacement: /api/v1/nodes/$1/proxy/metrics
        source_labels:
        - __meta_kubernetes_node_name
        target_label: __metrics_path__
      scheme: https
      tls_config:
        ca_file: /var/run/secrets/kubernetes.io/serviceaccount/ca.crt
        insecure_skip_verify: true
    - bearer_token_file: /var/run/secrets/kubernetes.io/serviceaccount/token
      job_name: kubernetes-nodes-cadvisor
      kubernetes_sd_configs:
      - role: node
      relabel_configs:
      - action: labelmap
        regex: __meta_kubernetes_node_label_(.+)
      - replacement: kubernetes.default.svc:443
        target_label: __address__
      - regex: (.+)
        replacement: /api/v1/nodes/$1/proxy/metrics/cadvisor
        source_labels:
        - __meta_kubernetes_node_name
        target_label: __metrics_path__
      scheme: https
      tls_config:
        ca_file: /var/run/secrets/kubernetes.io/serviceaccount/ca.crt
        insecure_skip_verify: true
    - honor_labels: true
      job_name: kubernetes-service-endpoints
      kubernetes_sd_configs:
      - role: endpoints
      relabel_configs:
      - action: keep
        regex: true
        source_labels:
        - __meta_kubernetes_service_annotation_prometheus_io_scrape
      - action: drop
        regex: true
        source_labels:
        - __meta_kubernetes_service_annotation_prometheus_io_scrape_slow
      - action: replace
        regex: (https?)
        source_labels:
        - __meta_kubernetes_service_annotation_prometheus_io_scheme
        target_label: __scheme__
      - action: replace
        regex: (.+)
        source_labels:
        - __meta_kubernetes_service_annotation_prometheus_io_path
        target_label: __metrics_path__
      - action: replace
        regex: (.+?)(?::\d+)?;(\d+)
        replacement: $1:$2
        source_labels:
        - __address__
        - __meta_kubernetes_service_annotation_prometheus_io_port
        target_label: __address__
      - action: labelmap
        regex: __meta_kubernetes_service_annotation_prometheus_io_param_(.+)
        replacement: __param_$1
      - action: labelmap
        regex: __meta_kubernetes_service_label_(.+)
      - action: replace
        source_labels:
        - __meta_kubernetes_namespace
        target_label: namespace
      - action: replace
        source_labels:
        - __meta_kubernetes_service_name
        target_label: service
      - action: replace
        source_labels:
        - __meta_kubernetes_pod_node_name
        target_label: node
    - honor_labels: true
      job_name: kubernetes-service-endpoints-slow
      kubernetes_sd_configs:
      - role: endpoints
      relabel_configs:
      - action: keep
        regex: true
        source_labels:
        - __meta_kubernetes_service_annotation_prometheus_io_scrape_slow
      - action: replace
        regex: (https?)
        source_labels:
        - __meta_kubernetes_service_annotation_prometheus_io_scheme
        target_label: __scheme__
      - action: replace
        regex: (.+)
        source_labels:
        - __meta_kubernetes_service_annotation_prometheus_io_path
        target_label: __metrics_path__
      - action: replace
        regex: (.+?)(?::\d+)?;(\d+)
        replacement: $1:$2
        source_labels:
        - __address__
        - __meta_kubernetes_service_annotation_prometheus_io_port
        target_label: __address__
      - action: labelmap
        regex: __meta_kubernetes_service_annotation_prometheus_io_param_(.+)
        replacement: __param_$1
      - action: labelmap
        regex: __meta_kubernetes_service_label_(.+)
      - action: replace
        source_labels:
        - __meta_kubernetes_namespace
        target_label: namespace
      - action: replace
        source_labels:
        - __meta_kubernetes_service_name
        target_label: service
      - action: replace
        source_labels:
        - __meta_kubernetes_pod_node_name
        target_label: node
      scrape_interval: 5m
      scrape_timeout: 30s
    - honor_labels: true
      job_name: prometheus-pushgateway
      kubernetes_sd_configs:
      - role: service
      relabel_configs:
      - action: keep
        regex: pushgateway
        source_labels:
        - __meta_kubernetes_service_annotation_prometheus_io_probe
    - honor_labels: true
      job_name: kubernetes-services
      kubernetes_sd_configs:
      - role: service
      metrics_path: /probe
      params:
        module:
        - http_2xx
      relabel_configs:
      - action: keep
        regex: true
        source_labels:
        - __meta_kubernetes_service_annotation_prometheus_io_probe
      - source_labels:
        - __address__
        target_label: __param_target
      - replacement: blackbox
        target_label: __address__
      - source_labels:
        - __param_target
        target_label: instance
      - action: labelmap
        regex: __meta_kubernetes_service_label_(.+)
      - source_labels:
        - __meta_kubernetes_namespace
        target_label: namespace
      - source_labels:
        - __meta_kubernetes_service_name
        target_label: service
    - honor_labels: true
      job_name: kubernetes-pods
      kubernetes_sd_configs:
      - role: pod
      relabel_configs:
      - action: keep
        regex: true
        source_labels:
        - __meta_kubernetes_pod_annotation_prometheus_io_scrape
      - action: drop
        regex: true
        source_labels:
        - __meta_kubernetes_pod_annotation_prometheus_io_scrape_slow
      - action: replace
        regex: (https?)
        source_labels:
        - __meta_kubernetes_pod_annotation_prometheus_io_scheme
        target_label: __scheme__
      - action: replace
        regex: (.+)
        source_labels:
        - __meta_kubernetes_pod_annotation_prometheus_io_path
        target_label: __metrics_path__
      - action: replace
        regex: (\d+);(([A-Fa-f0-9]{1,4}::?){1,7}[A-Fa-f0-9]{1,4})
        replacement: '[$2]:$1'
        source_labels:
        - __meta_kubernetes_pod_annotation_prometheus_io_port
        - __meta_kubernetes_pod_ip
        target_label: __address__
      - action: replace
        regex: (\d+);((([0-9]+?)(\.|$)){4})
        replacement: $2:$1
        source_labels:
        - __meta_kubernetes_pod_annotation_prometheus_io_port
        - __meta_kubernetes_pod_ip
        target_label: __address__
      - action: labelmap
        regex: __meta_kubernetes_pod_annotation_prometheus_io_param_(.+)
        replacement: __param_$1
      - action: labelmap
        regex: __meta_kubernetes_pod_label_(.+)
      - action: replace
        source_labels:
        - __meta_kubernetes_namespace
        target_label: namespace
      - action: replace
        source_labels:
        - __meta_kubernetes_pod_name
        target_label: pod
      - action: drop
        regex: Pending|Succeeded|Failed|Completed
        source_labels:
        - __meta_kubernetes_pod_phase
    - honor_labels: true
      job_name: kubernetes-pods-slow
      kubernetes_sd_configs:
      - role: pod
      relabel_configs:
      - action: keep
        regex: true
        source_labels:
        - __meta_kubernetes_pod_annotation_prometheus_io_scrape_slow
      - action: replace
        regex: (https?)
        source_labels:
        - __meta_kubernetes_pod_annotation_prometheus_io_scheme
        target_label: __scheme__
      - action: replace
        regex: (.+)
        source_labels:
        - __meta_kubernetes_pod_annotation_prometheus_io_path
        target_label: __metrics_path__
      - action: replace
        regex: (\d+);(([A-Fa-f0-9]{1,4}::?){1,7}[A-Fa-f0-9]{1,4})
        replacement: '[$2]:$1'
        source_labels:
        - __meta_kubernetes_pod_annotation_prometheus_io_port
        - __meta_kubernetes_pod_ip
        target_label: __address__
      - action: replace
        regex: (\d+);((([0-9]+?)(\.|$)){4})
        replacement: $2:$1
        source_labels:
        - __meta_kubernetes_pod_annotation_prometheus_io_port
        - __meta_kubernetes_pod_ip
        target_label: __address__
      - action: labelmap
        regex: __meta_kubernetes_pod_annotation_prometheus_io_param_(.+)
        replacement: __param_$1
      - action: labelmap
        regex: __meta_kubernetes_pod_label_(.+)
      - action: replace
        source_labels:
        - __meta_kubernetes_namespace
        target_label: namespace
      - action: replace
        source_labels:
        - __meta_kubernetes_pod_name
        target_label: pod
      - action: drop
        regex: Pending|Succeeded|Failed|Completed
        source_labels:
        - __meta_kubernetes_pod_phase
      scrape_interval: 5m
      scrape_timeout: 30s

Average memory usage- 1600-1800 Mi
Memory usage after removing the annotation- 1200-1300 Mi
This metrics is for our test cluster. In our production the usage is aroung 20Gi.

Hi Team,
any help will be appreciated in regards to this.