With the patches for bug #93261 (I guess only [os: Treat ssh as a non-local client (v4)]) DRI/DRI2 over ssh is now broken.
There are legitimate and (once) perfectly working scenarios where one would want DRI/DRI2 over ssh (e.g. containers running players/browsers with accelerated video support or opengl applications, etc.).
If I'm not missing any obvious solution, this patch should be reverted or non local clients explicitly allowed to use DRI/DRI2.
Some indicative output:
error: XDG_RUNTIME_DIR not set in the environment.
libva info: VA-API version 0.36.0
X Error of failed request: BadRequest (invalid request code or no such operation)
Major opcode of failed request: 153 (DRI2)
Minor opcode of failed request: 1 (DRI2Connect)
Serial number of failed request: 11
Current serial number in output stream: 11
$ LIBGL_DEBUG=verbose glxgears
libGL: screen 0 does not appear to be DRI2 capable