Tsdb backfill from openmetrics

trying Storage | Prometheus

“–storage.tsdb.retention.time=1y” retention set to 1 year

openmetrics data example

HELP user_accounts_total The total number of user accounts.

TYPE user_accounts_total gauge

user_accounts_total{product_id=“user_web”,service=“web”} 2760 1654120800

date -d@1654120800
Wed Jun 1 22:00:00 UTC 2022

but after prometheus reload i see lot of messages
ts=2023-03-11T15:19:33.368Z caller=db.go:1541 level=info component=tsdb msg=“Deleting obsolete block” block=01GV8M2W2RH4ZW31SVXZ7YSMC7

any tips howto debug why prometheus starts process of “deleting blocks”?