At one point I thought my video card is defective, but I came to the conclusion that it was just the video driver.
I tried to use Ubuntu on the USB stick and had the same problem.
So on Linux it is only working in safe mode.
I tested the video card in Windows 10 and it works normally.

Error:

[drm:amdgpu_init [amdgpu]] ERROR VGACON disables amdgpu kernel modesetting.

Maybe this:

Then you have to append nomodeset or eventually nouveau.modeset=0 to the kernel parameters of the live ISO.
just spam the space bar when the computer starts to show the boot menu then press e to add the extra parameters.

Only adding nomodeset may be enough, the other one is for nvidia cards

Or maybe: radeon.modeset=0 or both

Found this at: https://discuss.getsol.us/d/1019-black-screen-after-usb-boot-but-sound-works/4

Maybe it is the other way around, looking at your error, that you have to remove nomodeset parameters from the commandline... from the USB stick with Solus .iso,

I did take a look at the .iso , but there is no nomodeset kernel commandline there, so try to add those 2 mentioned above?

just spam the space bar when the computer starts to show the boot menu then press e to add the extra parameters

    RaMa solved the problem.
    I added the parameter to GRUB and it went back to work.

    amdgpu.dc=0

    In GRUB I selected the "E" key added the parameter and then Ctrl + X to run the system.
    To finish I had to save this change in GRUB using the grub-customizer.

      a month later

      Today, I decided to clean and dust the video card ...
      She returned to work normally, need not add the parameter.