See e.g. https://www.mediawiki.org/wiki/Talk:Download?action=history . There are lots of lines like [INVALID] edited the description . . (-13) or changed the topic title from "$5" to "[$3 $4]" . . (+6).
Lots of related log errors too, they look like:
Warning: Invalid parameter for message "flow-rev-message-edit-header": a:2:{s:10:"user-links";a:1:{s:3:"raw";s:305:"<a href="/wiki/User:Kghbln" class="mw-redirect mw-userlink" title="User:Kghbln"><bdi>Kghbln</bdi></a> <span class="mw-usertoollinks">(<a href="/wiki/User_talk:Kghbln" title="User talk:Kghbln">talk</a> | <a href="/wiki/Special:Contributions/Kghbln" title="Special:Contributions/Kghbln">contribs</a>)</span>";}s:9:"user-text";s:6:"Kghbln";} in /srv/mediawiki/php-1.29.0-wmf.7/includes/Message.php on line 1172