mpv got error (suddenly, may because after clang and/or LLVM update?)
libEGL warning: DRI2: failed to authenticate
libEGL warning: MESA-LOADER: failed to open swrast: libLLVM-13.so: cannot open shared object file: No such file or directory (search paths /usr/lib/dri, suffix _dri)
[vo/gpu] VT_GETMODE failed: Inappropriate ioctl for device
[vo/gpu/opengl] Failed to set up VT switcher. Terminal switching will be unavailable.
[vo/gpu/opengl/kms] No connected connectors found
[vo/gpu/opengl] Failed to create KMS.
Failed to open VDPAU backend libvdpau_nvidia.so: cannot open shared object file: No such file or directory
[vo/vdpau] Error when calling vdp_device_create_x11: 1
[vo/xv] No Xvideo support found.
[vaapi] libva: vaGetDriverNameByIndex() failed with unknown libva error, driver_name = (null)
[vaapi] Failed to initialize VAAPI: unknown libva error
[vo/x11] Warning: this legacy VO has bad performance. Consider fixing your graphics drivers, or not forcing the x11 VO.
How to solve it
Either your mirror is out of date, or you've done a partial upgrade. On my machine, ldd /usr/lib/dri/swrast_dri.so asks for libLLVM-14.so.
pacman -Syu should fix the issue.