Is there a reason why Prometheus chunk file size getting increased overtime

Hi all,

Our customer has been using the Prometheus for years. The configurations have not been changed since day 1 and recently the file system disk usage is over 90% and keeps increasing(not always right away but gradually). Is there a reason why new chunk size increases over time?

Although we have many application Metrics used to monitor our network elements and performances, they are never changed or added. We are just getting the same data KPIs over time.

So, is there a reason why chunk size increases over time? Any way we can sustain the file size w/o changing the retention time?