Pest eating my sps

[Kruss7]

This is precisely why I was asking about movement. When my birdsnest gets a bit too irritated like during water changes, some polyps will retract and shut tight, forming what looks like tiny black dots. They honestly look exactly like in the pictures provided.

I haven’t done a water change or been in the tank and my parameters look decent to me, but I won’t rule anything out. The issue I see is that it seems like there is some tissue loss.