iWatch Series 6 stuck at max brightness

I recently facing the same issue like yours. The brightness slider wont work, but the other settings are working well.

I suggest you to ask Siri on your Apple Watch to decrease the brightness to the lowest. And now mine is perfectly fine.

I do think that this is a bug or something since I have updated to the latest WatchOS 8.

Hello josuediaz91,

Welcome to Apple Support Communities!

It sounds like you're unable to change the brightness on your Apple Watch. We'd like to help.

Have you tried checking for any updates? If you have a watchOS update we would suggest updating as a first step.

Here's some information on how to Adjust brightness, text size, sounds, and haptics on Apple Watch.

Do you have any features such as Always On enabled? If so, turn them off. Are you able to change the brightness after doing this? Take a look at Turn on and wake Apple Watch to learn how to check this.

Have a nice day.

josuediaz91,

Does the screen brightness on your watch change on its own in different environments or lighting?

If you continue to have trouble with your Apple Watch, we would suggest contacting Apple Support. Here's how to Get Support.

Take care.

This is the ambient light sensor kicking in,this adjusts your screen brightness to match the surrounding area,there is no setting or configuration for this.