DitherTemporalAA's output contains some noise even when Alpha Threshold is set to 0.
Open the NewMaterial in the attached project to see white noise can be seen when thought Alpha Threshold is 0.
(Anti Aliasing Method is set to to None so that you can see the raw result)
Exprected result: DitherAA should output a clean mask without a noise when Alpha Threshold is 0.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-53219 in the post.