I was building in a ancient city when I came across chunk error-type things. I was fixing up some things in the sections the previous day and when I logged on today the placed where I had built were replaced with deepslate pillars. It only effected the underground, specifically the ancient city structure zone. It regenerated as if the ancient city was not there and looked like just a sculk cave was supposed to be there. Only a few chunks spread out around the area became deepslate. 

EDIT:   In 1.19.10 campsite and other blue wool stuff is ancient cities now here and I think the ancient cities I built at are regenerating to match 1.19.10 version but staying it the same space, I may have 1.19 and 1.19.10 city terrain