Change 528981 had a related patch set uploaded (by DannyS712; owner: DannyS712):
[mediawiki/extensions/AbuseFilter@master] Add content_model variable

https://gerrit.wikimedia.org/r/528981

Also, there is currently already new_content_model and old_content_model, which I assume are for log entries that change content models, but when examining a change content model log entry (like https://en.wikipedia.org/wiki/Special:AbuseFilter/examine/1172331730), neither variable is shown

I think there are some todos to actually set those variables for all edits, as having them for changeContentModel entries only wouldn't make sense in AF.
Next week I'll check and think about what we should opt for.

OK, so: new_ and old_content_model are for all edit actions, and the're correctly set within the hook handler. In fact, you can check that they're available when examinating an AbuseLog entry, random example. In the code there's the following comment: // TODO: set old_content and new_content vars, use them, but that's outdated and it just wasn't removed in rEABF1e550ddda9c6956bae412dc4c69b1cc7cf22b055 (which is where those variables were added).
Given that we already have these two variables, I find it unnecessary to add another one which is identical to new_content_model.
Instead, there are two separate bugs

1. The variables aren't set for uploads, and there's a todo for that.
2. The variables aren't set when examinating edits.

I believe that 1. is not urgent, and the todo comment is enough. As for 2., we need a way to retrieve the content model from a recentchanges row. This is definitely possible, but at a quick glance I'm seeing a long path from rc_this_oldid/rc_last_oldid, then maybe Revision::newFromId but that could fail for deleted stuff, and we can't use Revision::getContentModel because of MCR. Or maybe, from rc_this_oldid go to revision.rev_id, then we cannot use rev_content_model so we'd need to join with the slots table, then with content.content_id and then get content.content_model, which is too long to be true.
For the moment I can fix the comments.

Change 529605 had a related patch set uploaded (by Daimona Eaytoy; owner: Daimona Eaytoy):
[mediawiki/extensions/AbuseFilter@master] Remove outdated comment, add a new one

https://gerrit.wikimedia.org/r/529605

Change 528981 abandoned by DannyS712:
Add content_model variable

Reason:
Per phab

https://gerrit.wikimedia.org/r/528981