Hello, have you tried this? https://iristech.co/how-to-test-my-lcd-monitor-for-subpixel-flicker/
It doesnt show any flicker on waterfox on my trusted laptop. On new firefox that is painful it shows banding on 2a,b and 4a,b.
martin That's LCD inversion flicker it's testing for I think. more info here
One thing to keep in mind is that the info at that link is old, doesn't cover PWM, etc.
I know another pattern that might make your screen flcier.
PHOTOSENSITIVE EPILEPSY WARNING.
It's the default X11 desktop pattern for when a window manager isn't set, but I've always found it obnoxious.
Lagom.nl's inversion test makes my whole screen turn green when scrolling down enough so that a large portion of the screen is covered by the grey background image. It's grey like it should be but after like 80% are covered, suddenly it turns green. Not sure what's going on. Must be some monitor internals.