kernel 6.1 or 6.2 will change how laptop backlight is handled and it might negatively affect some laptops, especially older ones. Hans De Goede, the developer of that change, asks for wider community testing. Here are his blog posts containing all necessary instructions:
If you can, please help him identify affected laptops, so that this change can be prepared with a minimum negative impact. All results are to be submitted directly to Hans (not to this list), as described in the blog posts.