Hello,
I have tried to implement reflection with webxr. This works well on desktop browser, but when tested on my Oculus Quest 1 it is flickering strongly. Here is an example which reproduce the problem:
Hi @Deltakosh, thank you for ping @RaananW, but looks to me that he is not available. Could be that somebody else know how to fix the problem or at least if webXR support reflection surface?
Cheers
Not sure why you think I am not available 
The oculus seems to have a bit of a hard time when setting blur kernel. Try without, and it works as expected - reflecting_ground | Babylon.js Playground (babylonjs.com)
I will try contacting them and see if they have any input regarding that.