Are you lighting your scene with a HDRI or skylight? Are you using RTGI? I had similar issue with skylight + RTGI, you’ll get halos and other artifacts…so I disable skylight.
Try isolating the rendering features and light to see what is causing the problem. Try lighting with lights, turn off everything else(RTGI,reflection,AO,post process).
edit: I think it’s related to the RTGI(it’s really experimental feature). See my attached pics. The one with the black arrow is RTGI = ON, the other one is RTGI = OFF.
