Brightness issues with Series X?

Could you try navigate in your TV until you can find that game mode?
Maybe it resets by accident

Hi there! This is Ronnie, your fellow Xbox gamer.

Nice to meet you and I hope you are having a great day!

I understand you need help video issue with the Xbox.

Try to do a reset on the console and see if this can help with the brightness issue.

NOTE: This will remove the profiles on your console, make sure that you remember the email and password to your account.

No data or game saves will be lost doing this, everything is backed up to the cloud servers.

1. Press the Xbox button to open the guide.

2. Select Settings.

3. Select System.

4. Select Console info

5. Select Reset console.

6. Select Reset and keep my games & apps

This will also help sync the data on your console properly.

If this does not help, try using a different HDMI cable or try playing the Xbox on another TV.

Hope that helps.

Try to turn off the console and remove the power cord; wait for 1 to 2 minutes before plugging it back in and turn on the console!

If the issue persists, you might want to soft reset your console!

I'm having the same issue I've tried display settings on both the tv and xbox nothing is working it seems some apps such as hulu or hbo max work fine but then others such as netflix and disney have the issue same with some games work others don't

That’s the thing i never changed my settings. I did a hard reset/full shut down and still its happening. Even in game when i open the guide that’s bright too. My tv auto switches to game mode so perhaps there is a setting there