GUIUtility errors when rendering mode is Multi Pass

[nomad512]

These errors occur repeatedly in editor and in builds when attached to a Rift or WMR HMD, but only when rendering Multi Pass.

The errors do not appear to affect performance or rendering but SteamVR+Unity seem to be less stable (very frequent crashes on Play and Stop) and the continuous console error spam is a concern.

Unity 2020.3.4f1
OpenVR XR Plugin 1.1.4
XR Plugin Management 4.0.6