I have a Thinkpad P14s Gen 6 with IPS screen. The weird think is that I can better use it at full or close to full brightness. If I reduce brightness it gets harder and harder to use. The notebook is said to not use PWM even in lower brightness settings. So this should not be the issue here. The colors are generally very oversaturated and I use an app to reduce saturation.
The reduction in brightness looks like there are gray layers put on top of the screen. It just gets duller and duller. Same with night light settings. It does not alter the colors but puts a layer of yellow on top.
Does this description sound familiar to someone?
I use incadescent lightbulbs and the room is generally darker. So I would normally not use full brightness.