How does latest CU change Search Indexer?

I got KB5014019 yesterday and ever since Microsoft Windows Search Indexer has been running using 4% CPU (I know, not a lot) but its about 9 hours now.
I have since got KB5014697 thinking it might fix it. But no.

If it included a rebuild of index then maybe I can understand it?

guess I could just leave PC idle and see if it stops.

it seems to run more often now, I noticed it running on Saturday so I tried a few fixes such as SFC and the troubleshooter. Its running again now which seems too soon.
I don't see anyone else mentioning it though. I will see if rebuilding index fixes it.

So i spent 8 hours or so rebuilding the search index, restarted PC just to find the process is still running.
It got to 43509 when rebuilding. Which confuses me as its currently showing indexed as 43480 with 1063 items in pending.
How do I tell if this is total? or if its going to find more tomorrow?
How can it have found more in the rebuild than are there now?

I disabled the service as it seemed to find new files every day.