The far biggest concern is the Naso tang in a 75gal!!!
(kidding, well, sort of...)
I really have no idea where to look in the pic. I do kinda see two green mushroom looking spots and a pink spot on the rocks.
If the leathers are small, I really wouldn't worry too much, some small corals aren't going to nuke a 75gal. Perhaps run some carbon as extra insurance, and hope they come back, especially if the only other corals are those brown polyps, you aren't keeping like SPS in there too....
If they were fairly large, considering removing them if they look like they aren't going to make it.