This should be addressed as part of a much needed overhaul of tag validation, specifically T173917 and T154749

Change 700850 had a related patch set uploaded (by Matěj Suchánek; author: Matěj Suchánek):

[mediawiki/extensions/AbuseFilter@master] Clarify ChangeTagValidator::validateTag and disallow user-defined tags

https://gerrit.wikimedia.org/r/700850

See also T247049: Unable to remove manually applied tags used by edit filters.

Occurrences across wikis: P56851 (111 filters on 40 wikis)
Query:

SELECT afa_filter, ctd_name
FROM change_tag_def, abuse_filter_action
WHERE ctd_user_defined = 1
AND afa_consequence = 'tag' AND (
  afa_parameters = ctd_name
  OR afa_parameters LIKE CONCAT('%\n', ctd_name)
  OR afa_parameters LIKE CONCAT(ctd_name, '\n%')
  OR afa_parameters LIKE CONCAT('%\n', ctd_name, '\n%')
);