This was discussed in another thread with the proposed solution being unpack the new binary from their github and copy it over the old old. This is not working for me. Perhaps permissions issues?
I had to edit my boot config to get my mouse working per that other thread and I still have that change in place with the OS if that matters.
--- from other thread ---
Hi there! New Linux requires new Amiberry. Please grab it from here: https://github.com/BlitterStudio/amiberry/releases/download/v5.4/amiberry-v5.4-rpi4-sdl2-64bit-manjaro.zip
Unpack and copy the binary to Amiberry folder and replace the old Amiberry there.
EDIT: Also copy new Amiberry/data folder. Otherwise Amiberry window might be closing because of missing png and icon files.
Hope it helps?