This is not a regression. Tested in //UE5/Release-5.2 CL26001984
After assigning an IES Profile to a light the icon for that profile updates to a gradient bloom preventing the profile from being preview by the icon.
Expected Results:
The icon for the IES Profiles remains the same allowing the user to preview the result of the profile.
Actual Results:
The Icon updates to a gradient bloom.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-195365 in the post.