Yeah I’m not sure I buy into this theory - there’s really little difference between this shader and displaying a pure red or a pure green or pure blue screen - just one out of four pixels are black in the horizontal direction is the only real difference.
I’m not sure there’s anybody that says don’t display a pure colour screen due to risk of burn in. In fact we’re turning off the majority of sub pixels so it’s even more unlikely to raise temps as to damage displays. LCDs in particular are lit by comparatively large lights behind them so they don’t really have the control to damage individual cells as in the above description.
In your particular case youre using an SDR IPS display and I’d imagine its pretty much impossible to have burn in on that display. Even an OLED probably wouldn’t have problems.
As to why you’re getting flickering I’m not sure - do you get flickering if you display a red, green or blue screen? My IPS is fine at displaying all those patterns that you linked so it might be hard for me to correctly diagnose this - it does feel like a display level issue. I presume you’re using the SDR version in all this?