https://bugs.freedesktop.org/show_bug.cgi?id=109001
--- Comment #8 from Michel Dänzer michel@daenzer.net --- I suspect disabling V-Sync in xfwm4 just avoids the problem, i.e. it's a workaround, not a fix. Unless you're using rotation or other RandR transforms, leaving V-Sync enabled and leaving TearFree at the default (auto) might also avoid the problem, and would be more efficient.
Does https://gitlab.freedesktop.org/xorg/driver/xf86-video-amdgpu/merge_requests/... help by any chance?