Comment # 5 on bug 1207388 from Patrik Jakobsson

If the firmware is not loaded the screen gets frozen during boot. So I'm
assuming he's got the right firmware files installed.

Unless there is a specific reason for running the amdgpu ddx driver I would
recommend using the modesetting driver instead. Or even better, use Wayland. I
don't think there is much development happening on the amdgpu ddx driver.

Bj���rn, if you really would like to have this issue fixed I would recommend
reporting this to upstream at:
https://gitlab.freedesktop.org/xorg/driver/xf86-video-amdgpu/-/issues

They are in a much better position to fix the bug.