Versions mentioned in the description apply to the upstream
Remediation section below for
Debian:9 relevant versions.
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).
mediawiki to version 1:1.27.7-1~deb9u7 or higher.