chief The build repo is made public so those are willing and able to help with testing have access to it. It is certainly not suitable for end users. Things WILL break in build and packages WILL need to be removed due to issues they create. That is why you need to subscribe to the testing section of this forum, there any breakage/issue is always announced. If you do not wish to subscribe or help with testing, please remove build from your pacman.conf.
Also, this is the complete wrong thread to mention this, has absolute zero to do with ISO testing, so no choice but to close this thread now. If you have questions, continue in the already opened linux-firmware thread linked above.
fjmorazan Always run pacman -Suu when on build and a package is removed, do not ignore such package. Breakage in linux-firmware is now confirmed for more hardware then just amdgpu. Helping with the build repo also means running exactly what is in the KaOS repo.