Good spot! It’s an error in the primary mirror segment phasing.

The observatory has to phase the mirror segments periodically, and it’s a bit of an art as well as a science. For a while, something was happening with their algorithm and procedure that was leaving those spots. Some of us (hi) did complain and it was fixed for the most part. It did come back a couple times though….

The slightly incorrect phasing produces those spots. It’s conceptually like a diffraction spike.