Is the screen brightness not adjustable on the laptop?

My laptop's screen brightness can't be changed. I set the lowest level yesterday, but otherwise didn't do anything unusual

When I press the buttons, the bar appears showing what the current brightness level is. This also changes on the bar. But the actual brightness remains the same.

I also have the same problem in the settings. A restart does not help. Has anyone had a similar problem and / or does anyone know what I could try to solve?

If you use windows 10 this might help https://windowsunited.de/loesung-bildschrimhelligkeit-laesst-sich-nicht-aendern/