https://immersive-web.github.io/webxr/#dom-webglrenderingcontextbase-makexrcompatible step 1.8.1 says:

Force context to be lost and handle the context loss as described by the WebGL specification.

where "handle the context loss" links to https://www.khronos.org/registry/webgl/specs/latest/1.0/#CONTEXT_LOST

Those steps set some flags, then queue a task to fire an event. But step 1.8.2 seems to assume the event has already fired (it hasn't; there's just a task queued to fire it). Furthermore, when that task runs, it will restore the drawing buffer, but step 1.8.3 does that too.

This section seems like it wants to reuse parts of the default webgl behavior, but not all of it. The right way to do this is probably to factor out the to-be-shared behavior (if possible), or something. But the current setup really doesn't make sense.