When looking at All-Users.git I have found a bunch of obsolete references under refs/starred-changes/xx/yyyyxx/zz which were to track which files got reviewed. The last change having such entry is 709572 made in August 2021. That seems to match our upgrade to Gerrit 3.3 ( T262241#7256043 ).
My guess is tracking reviewed files got moved out of the git repository. We should be able to garbage collect any reference pointing to an object having reviewed/.
git fetch origin --prune +refs/starred-changes/*:refs/remotes/origin/starred-changes/* git ls-remote . refs/remotes/origin/starred-changes/*|sort -g -t/ -k6|egrep -v '^(8485e986e458a566e6f6160f71d704edc10c57fc|ce7b81997cf51342dedaeccb071ce4ba3ed0cf52)'|less|wc -l 1568
The checksum are for git blobs:
$ echo -en 'blob 4\0star'|shasum ce7b81997cf51342dedaeccb071ce4ba3ed0cf52 -
$ echo -en 'blob 6\0ignore'|shasum 8485e986e458a566e6f6160f71d704edc10c57fc -
Though some entries have both star AND reviewed/XXX so it is not that straight forward :]