Per request at [[WP:RAF]], the removal of all categories in an article often implies vandalism.

Fix redirect catcher and exclude large deletions targeted elsewhere. -DF

Setting to warn. Not a single false-positive in the last 100 hits. --Conti

Using message MediaWiki:Abusefilter-all-categories-removed - Cenarium

add tag "categories removed" - Cen

I added "stub}}" to the exceptions. - Ruslik

I added the "{{uncat" - usually if a new user adds this, (s)he is familiar enough to know what (s)he's doing.

(article_namespace == 0) &

!("autoconfirmed" in user_groups) &

(edit_delta > -2000) &

!contains_any(lcase(new_wikitext), "[[category", "#redirect", "stub}}","{{uncat")