If you're missing GPU firmware you should install 'firmware-amd-graphics <https://packages.debian.org/unstable/firmware-amd-graphics>'. If you're still having a problem with missing GPU firmware after that is installed you should share your package listing and kernel log as attachments.
99% of the time ACPI BIOS errors are firmware bugs. You should look
into upgrading to the latest firmware from the manufacturer. Note: not
all manufacturers support LVFS, you might need to check their support
site. In any case those should be red herrings to your issue.
