Based on a tip I appended "nomodeset" to the kernel boot parameters and that fixed the brightness but introduced graphics corruption like seen in the attached screenshot.
After removing "nomodeset" and rebooting I am for the first time using the system without a sign of the bug in question (which of course makes sense seeing as I *just* decided to file a bug for it. I didn't know Murphy's law applied to open source development...
Based on a tip I appended "nomodeset" to the kernel boot parameters and that fixed the brightness but introduced graphics corruption like seen in the attached screenshot.
After removing "nomodeset" and rebooting I am for the first time using the system without a sign of the bug in question (which of course makes sense seeing as I *just* decided to file a bug for it. I didn't know Murphy's law applied to open source development...