Opera GX seems to support Nvidia RTX VSR.
It seems that Opera GX supports RTX VSR as of now, version:
LVL 4 (core: 98.0.4759.74)
I didn't test earlier versions, i recently switched again to opera gx
I tested by taking a screenshot on 3 different browsers, with the same video at the same quality, Edge and Opera GX 2.5 MB Firefox, that still doesn't support RTX VSR , 2.0 MB.