Did you test the flickering screen on a different laptop right after the flicker started while connected to the m1? The reason I ask is because several users (including myself) have the m1 causing flicker and image retention that persists on the screen even when you connect the screen to a different laptop after the fact. The flicker/retention goes away after powering off the screen completely for a while.
Even in my case, the m1 would cause my screen to flicker and image retention which would persist when I would immediately disconnect the m1 and switch the screen to a different windows machine (even on a different port, hdmi to dp).
I've returned my m1 and its been more than 2 weeks now with no issues anymore with my ultrawide connected to my windows machine as usual.
I disconnected my laptop and then I connected another M1 based laptop to the same screen using the same USB-C cable. Weird that the screen would retain the flicker even with a different laptop? 🤔 I've tried "rebooting" the screen, and swapped the cable but the flicker was still there.
Though the flicker went away after a while, and has now been gone since my last post. It seem to do this once in a while, though I can't confirm if it is the screen or not, since I plugged in my laptop on another screen (another model too) using USB-C and it did not flicker then. The screen did continue to flicker on it's own though, unconnected. So this to me says it's something wrong with the screen and not the same issue?