Looks like some sort of favia or favaties, at least that what they are called in the hobby in reality most belong to different genera after reclassifications.
Could you share some details on your water parameters?
White light pics to better show the algae would help too, looks like maybe dinoflagulates, some species can sting which could explain the die back.
I wouldnt give up hope for the this coral, favia are very resilient ime. First thing I would do is a peroxide dip to remove this algae, and then adjust your water parameters if needed. I'm sure others will chime in on ways to combat dinos, in my experience they will fade away if you keep your parameters in check, particularlyby keeping your nitrate and phospahte above zero, just part of having a new tank.
Heres the source I use for peroxide dips
https://humble.fish/community/threads/peroxide-dipping-guidelines-for-corals.4715/
