I'm also seeing this on my local x86_64 machine when running:
VK_DRIVER_FILES=/usr/share/vulkan/icd.d/lvp_icd.x86_64.json LIBGL_ALWAYS_SOFTWARE=1 GALLIUM_DRIVER=softpipe /usr/libexec/installed-tests/gtk-4.0/gdk/memorytexture
Both the ngl and the vulkan r16g16b16-float tests often fail on softpipe and lavapipe respectively. llvmpipe seems unaffected instead.
