Hi! Just tested and H265 encode has a black frame insertion issue I think? Every other frame seems to be a black frame and it causes massive image flickers when the video plays. H264 with all other settings the same doesn't cause this issue.
Are you using the same input to test the H264 and H265? It may be a problem with the input, or some bug. Can you share the input video if its not private?
It's the same input, only thing I changed was the codec. It was just a random Instagram story video I downloaded to try this on, don't remember which it was anymore. I'll try other videos and see if it happens as well.