Eg. in this diff page https://www.wikidata.org/w/index.php?title=Q109044698&diff=prev&oldid=1566421192&uselang=da , the date is "14 July 1971" in the summary and should be "14. juli 1971" like for the core diff below it.

@Tinyttt I finally found a working configuration.

Same here. I get this from logs:

I have experienced this too, and have rollbacked to previous version while waiting for patch.

It would be possible to let the user specify in a form which category to excude. But as far as I know, MW should not implement recursive category querying for performance reasons. In this case, excluding a single category would be unuseful.

I am not the author of the diff so I can't confirm my hypothesis, but it is plausible that the same phenomenon happened in both cases: insertion of an « empty » object (that was duely removed) as the only content of the problematical «p» or «ref» tag, the latter then only trimmed instead of removed. Is that possible?

It seems the VisualEditor is generating new Lint Errors. This should be fixed before deployment. T164053

One edit with the VisualEditor recently inserted «p /» in the wikicode, and the article then appeared in the Lint Errors.

In fact, the bad handling is happening sooner than this line. Arabic has $useLinkPrefixExtension = true because determiners may not be separated from the nouns. As soon as the regex $e2 is used in the Parser to redefine $s, the last word of the article is considered as a prefix for the "link" of the category and therefore disappear with this link (print($s) just after the regex shows that the last word has disappeared at this point).

It comes from the source code of https://zh.wikipedia.org/wiki/Template:Selflink