On frwiki, we have false positives on a filter that tags edits that remove all categories.
Filter: https://fr.wikipedia.org/wiki/Sp%C3%A9cial:Filtre_antiabus/14
Example of false positive: https://fr.wikipedia.org/w/index.php?title=Bertrand_Chameroy&diff=prev&oldid=109458887 (it should not have the tag "suppression des catégories")
Details of the AbuseFilter log event: https://fr.wikipedia.org/wiki/Sp%C3%A9cial:Journal_du_filtre_antiabus/1204633
I am sure that this is not an error in the filter itself, because in the details of the AbuseFilter log event, the diff shows that categories are indeed removed. But this diff does not match the real diff, where categories are unchanged.
Expected behavior: the content of the 'new_text' variable of AbuseFilter should always match the new page text.
I found 4 such false positives for this filter in the last two months. In all cases, modification also has the 'VisualEditor' tag, so this could be related.
Other cases:
https://fr.wikipedia.org/wiki/Sp%C3%A9cial:Journal_du_filtre_antiabus/1200961
https://fr.wikipedia.org/wiki/Sp%C3%A9cial:Journal_du_filtre_antiabus/1190456
https://fr.wikipedia.org/wiki/Sp%C3%A9cial:Journal_du_filtre_antiabus/1164028