Hello Blero70.
Thank you for using Apple Support Communities. We'd like to recommend some steps you can try to see if we can get this issue sorted out. First, see if you're able to adjust your settings. Follow these steps here: Adjust the screen brightness and color on iPhone - Apple Support
See if you're able to manually disable Dark Mode. go to Settings > Display & Brightness and under Appearance, select Light and disable Automatic. Do you see any change? Additional steps you can try can be found below:
1.) Restart your iPhone - Apple Support
2.) Update your iPhone or iPad - Apple Support
1.) Back up your device using iCloud or your computer.
2.) Plug your device into power and connect to the internet with Wi-Fi.
3.) Go to Settings > General, then tap Software Update.
4.) Choose the software update that you want to install. You can choose to stay on iOS or iPadOS 15 and still get important security updates. Or you can choose the option to upgrade to iOS or iPadOS 16.
5.) Tap Install Now. If you see Download and Install instead, tap it to download the update, enter your passcode, then tap Install Now. If you don't know your passcode, learn what to do.
We hope these steps are helpful. Cheers.