Rotating tarball archives
Dated archives are easy to reason about: one file per day, named by date, removed by age. A weekly copy on Sunday and a monthly copy on the first of the month make a simple grandfather-father-son scheme.
tar --zstd -cf /backups/daily/$(date +%F).tar.zst -C /srv data
find /backups/daily -name '*.tar.zst' -mtime +7 -delete