The AbuseFilter variables added_links and removed_links don't seem to work (are always empty), also all_links seems to equal old_links. This is Wikibase specific, as it works with wikitext pages.
|Open||None||T76230 [Epic] data quality and trust|
|Open||None||T65632 AbuseFilter *_links variables incorrect on item edits.|
This can be fixed by either making Wikibase hook into AbuseFilter's "AbuseFilter-interceptVariable" hook (that might get messy). Or by doing some more work on ContentHandler support in AbuseFilter (which is also going to be a pain, given the way AbuseFilter "works").
I'm sorry, I'm pretty ignorant about wikidata. How exactly am I supposed to reproduce the problem? I tried here, but I'm unsure if that's right. If it is, then indeed we don't get _links variables.
Update: well, TBH I see some checks for ContentModel === Wikitext in the code used to retrieve links...