Have you tried live booting another distro?
Maybe the new KDE Linux is a good canditate. It comes with the same DE and has the newest testing versions of everything and might have a bugfix included. Also it’s arch based so there might be some default config that is different compared to what comes with debian.
Is maybe the light sensor controlling it? (if your laptop has one)
Sounds like when the brightness that the screen emmits changes, the sensor picks that up (in a darker environment?)
For a debugging step, try covering it with your fingers and check whether it still happens.
This means there’s a metadata inconsistency: a reference to a block group (allocation unit) that isn’t actually present in the filesystem. Essentially, the filesystem bookkeeping is pointing to something missing.
There were errors, but since check by default is read only, no changes were made.
replace mountpoint with where that drive is mounted and try:
sudo btrfs scrub start -Bd /mountpoint
this should fix the inconsistency iirc
Or alternatively:
sudo btrfs check --repair /dev/sdb1
but this is scarier since it might result in data loss
Don’t fuck with arch packages. Trying to resolve and maintain that dependency hell will be an unworkable nightmare.
If you only need libfdk-aac occasionally you can go with a docker container https://hub.docker.com/r/jrottenberg/ffmpeg
Example:
docker run -it --rm \ -v "$PWD:/data" \ jrottenberg/ffmpeg:snapshot-scratch \ -i /data/input.mp4 -c:a libfdk_aac /data/output.m4a