Ive got the same issue with my "Macbook Pro 13" M1 2020". I normally work with Premiere Pro on my windows machine. But now i got this laptop from work. Everything i export or make proxy, makes some flickering. I thought I was doing something wrong, but I can't find the issue. So I tried to open a project, that i know works 100% on my PC, and when I opened the project om my MacBook Pro 13", exported it, and now the video makes som flicker/jitter as you can see at the uploaded image. I just can't figure it out why this happen.
Same Issues still. It's May 2022 and when I export videos with the M1 Pro 2021 Version my edited 5K files (RED RAW) are flickering as hell. If I scale it down to HD it's having more troubles. If I export it with hardware encoding, than chances are better. Media Encoder also raises the chances. But still it's a 9/10 try to get it without problems. With Software encoding it gets definitely worse. Always used H264.