Honestly there are so many issues if you have two 4K screens on a MBP M1.
Just pay for the extremely expensive Apple screens and you might be ok. Otherwise except the worst.
My favourite: Dell 4K screen start scintillating, with extreme ghosting which is still present during reboot only to be fixed by using the degausser program and generic "Color LCD" color profile.
I’m running 3 4k screens (2 real 4k screens and one 3840(ish, can’t quite recall)x1440 in vertical orientation) on my Studio. One of the real 4k screens is an Asus, the other is an old Sharp monitor that can only do 30fps (fine for coding on).
I have no problems, and since they’re all pulling multiple duty through various connections, one 8-way KVC and one 4-way KVC, and are switched from machine to machine regularly, I’d have thought I’d be one of the first to find out…
I have this ghosting issue too. A bunch of us have been trying to get to the bottom of it here: https://forums.macrumors.com/threads/m1-air-ghosting-flicker... – It only affects M1 Macs, and seems to be unrelated to the brand of display. No replicable solution found so far. Incredibly annoying.
Just pay for the extremely expensive Apple screens and you might be ok. Otherwise except the worst.
My favourite: Dell 4K screen start scintillating, with extreme ghosting which is still present during reboot only to be fixed by using the degausser program and generic "Color LCD" color profile.