My touchscreen did this from the start, in the evening, at twilight, it just starts to dim for a few seconds and then brightens up and dims again until a certain light threshold is reached and it recovers normal functionality. If I cover its light sensor it brightens accordingly, it’s just a certain exterior light level it doesn’t like. I suppose it’s impossible to fix/adjust but maybe someone has an idea?

What about the light settings in the sub menu's

Yes tried that but it still dims/brightens even at lower or higher settings...

It's like I would like to raise the light level that the auto-on headlights come at, I think they come on too late, it's almost dark by the time they switch on. I tried to get the dealer to adjust it on my RRS but they said it wasn't possible. These days I don't bother with the auto-on setting, I drive around all the time using dipped headlights, roll on proper DRL's as bright as Audi and Mercedes fit to their cars. 2018 Mini Countryman Cooper S E All4 PHEV in Melting Silver - it’s whisper quiet in EV and polluter modes

I do not think it's impossible, but I also think that nowone can do it....

Mine suffers from the same, it dims and undims very quickly. It almost reacts to street lamp posts...
But, as far as I remember, when new, it had a very soft dim, something that you couldn't see, except the fact that the screen seemed the same under darkness or under the lights.

Must be something to do with the sensor and it's communication with the ECU.
Told the guy at the service that the car did this, and it came back the same...

I will try to blacken the sensor today and see what happens.

Obstructing the sensor only made things worse, the screen was washed out so I’ll live with the dim/undim at twilight for now…