Try Furan 2 dips, dips in coral revive, and chemiclean. Chemiclean seems to be a hit or miss with helping zoas. I've tried it and noticed that my healthy ones looked better, but sick ones did not really improve noticeably.
Dipped another and found this little thing plus another baby one. Haven’t noticed these before. Maybe an 1/8” mostly flat. Can’t seem to find anything similar online?
Finally think I may have found the “problem”. Relocated my Coral Banded Shrimp a couple weeks ago bc I noticed her roaming around these Z/Ps a lot at night. Wether she was looking for uneaten food or the Z/P were in fact the food she wanted I’m unsure, however since removing her most of the polyps have healed and I haven’t noticed any new damage to other polyps.