Anyone experience this on their iphone 12 ? I just noticed this slight difference today, when I'm in a well lit room or there's light, the screen becomes brighter, when i'm in a place that doesn't have enough light, the screen becomes darker, all the while my brightness stays the same.

I set true tone or any of those sort of things to OFF, so I have no idea why my screen would "change" on it's own ?

It's off. My situation is not that the brightness / darker goes down and up gradually, it just one moment blink and becomes brighter, one moment blink becomes darker. Not gradually.

All is off, every settings that is supposedly affected what I'm experiencing is off. But I did a restart on my phone, and problem solved surprisingly, not sure why.