Why of course? Stadia is using Linux. Using Windows is a waste of license fees for such services.
Stadia does use Linux, however Stadia has made an enormous number of missteps and seems very close to DOA so I'm not sure they're a good example of much.
For the reference, RTX shouldn't depend on the OS, since it's supported as a Vulkan extension.
Not that I like Stadia to begin with. They help Linux gaming only tangentially. But what they do actually helps in some way, rather than harms like Nvidia.
How would you expect all those Windows Games to be Streamed and played?