While it would be interesting to figure out the User::getActorId lock wait timeout, I see only 5 in the linked timeframe (and only 6 in the past 24 hours). They seem related to the same Special:Import as the rc_this_oldid error mentioned, but it's not obvious to me how or why. Most seem to be from job runners trying to process CategoryMembershipChangeJobs after the fact, just one is directly from the import.

There are many of the rc_this_oldid error you mentioned, all from the same request using Special:Import. The use of DeferredUpdate is obscuring the source of the insertion, but I'd guess it's probably that a code path can reach ImportReporter.php line 161 with $nullRevId being null (which should be fixed somehow, the method called on line 161 doesn't accept null). Based on other log messages in the same request, that seems like it in turn was probably caused by the same failure-to-load that's behind T205675 (see T205675#4723071 in particular) causing $nullRevision to not be created.

It is ok to close it if it is a duplicate or you think is unlikely to happen again or is a very rare occurence. I just report when I see something out of the ordinary on the logs FYI, but lack the knowledge of a deep analysis.

There are two parts here:

1. Fix ImportReporter to handle $nullRevId being null in some appropriate manner.[1] This task could be used for that, or we could make a new one.
2. Figure out what's going on with T205675 to fix the underlying cause. That should be done in that task.

[1]: @#core-platform-team: I don't know what would be best here: passing 0 to mean "no revision" in the RC entry, loading the ID of the top revision of the page in the absence of a null revision, or throwing an exception due to the failure to create the null revision.

@PlatformEng Note my previous comment at T227739#5327312, as the original reporter, which are in line with @Aklapper comments.