It’s normal?! That’s bizarre. It’s a completely stable image throughout on my CRT and on the previous firmwares. I’ve just rolled back to 0.75 and taken a video to prove this – make sure you watch it in 1080p60 mode:
So no, it was literally PERFECT on the old firmware. Perfect image, no unstable top portion – just perfect.
I’ve only ever experienced the unstable top part of the image on the 0.76 firmware. Nowhere else. It was also completely stable on my Framemeister (which I have since sold).
In any case, now I’ve rolled back to 0.75 and NES is flawless again. Hm. I’ll wait and see what happens with the next firmware, but the NES is the deciding factor in my case. There’s no point in updating if 1 out of my 8 consoles hooked up to the OSSC is worse off.