MediaWiki before 1.35.1 blocks legitimate attempts to hide log entries in some situations. If one sets MediaWiki:Mainpage to Special:MyLanguage/Main Page, visits a log entry on Special:Log, and toggles the “Change visibility of selected log entries” checkbox (or a tags checkbox) next to it, there is a redirection to the main page’s action=historysubmit (instead of the desired behavior in which a revision-deletion form appears).
lists.debian.org/debian-lts-announce/2020/12/msg00034.html
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/STT5Z4A3BCXVH3WIPICWU2FP4IPIMUPC/
lists.wikimedia.org/pipermail/mediawiki-announce/2020-December/000268.html
phabricator.wikimedia.org/T205908
www.debian.org/security/2020/dsa-4816