See attached video.
Happens always in editor, will also happen in standalone game but only if viewport rect has not the full window size.
The issue was not present in 4.22.
A large gray radial glow flickering on and off as the camera moves in particular directions, only present when there is a directional light with light shaft bloom enabled.
Results: As you move the camera, you should see the gray flickering artifact appear.
Expected: In an empty scene, the light shaft bloom shouldn't show at all, because the bloom shouldn't do anything to a pure black background.
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-86015 in the post.