Sentry-data volume cleanup

I got getsentry/onpremise 20.10.1 version installed.
I wonder how to perform a cleanup of old data from sentry-data volume.
My retention is set to 35 days, which affects postgres data, but not the data stored in sentry-data. Is there a way to delete old data safely?

There is a sentry-cleanup cron set up to do this: onpremise/docker-compose.yml at f2e2dc2bb3c0c2505d0a6044989bdd29c7905fef · getsentry/onpremise · GitHub

Does that not work?

Apparently not, this cron job fires up each day and there is no error in logs from its execution.
Nevertheless sentry-data/_data/files volume contains old stacktraces and grows upon time constantly.

Anyone experienced same issue?