Thanks for the report! There are a number of known issues with the current update process for WDQS. We are rolling out a new updater for WDQS that should be out in the next couple of weeks, so we'll not investigate this further on the WDQS side.

The Search indices are updated via a different process, which should be a lot more robust. It is unexpected to not see updates on the Search side, we'll investigate that further.

If this problem happened for both CirrusSearch and WDQS I suspect a problem with changepropagation and/or eventgate.
WDQS have been reloaded and no longer shows the problem.
Search does still have the revision 1412772598 in its index while 1502388913 is expected.

Checking SAL I don't see anything obvious.
Checking logstash for this time period I see nothing.
Checking event.mediawiki_revision_create I can't find this revision either, even scanning one day before and after:

spark.read.table('event.mediawiki_revision_create').where('year = 2021 AND month=9 and day in (23,24,25) and rev_id=1502388913').show(10, False)

shows nothing.

Note that the search index will correct itself at some point, @Mormegil please let me know if you want me to force refresh this specific item.

I'm closing this task as a duplicate of T215001 as I believe this is the root cause.

please let me know if you want me to force refresh this specific item.

That’s not necessary for me, thanks!