Hey guys. This is wifi, pixel 2xl with stadia raiju, wired earphones. And also my pc with wifi.
On chromecast ultra with ethernet connection, this is perhaps slightly less noticable, but I'm not sure as I haven't played stadia on my tv lately.
Also yes it happens on all games the same and equally. Tho lagging from wifi can sometimes worsen the sound going more out of sync. Reopening stadia application often improves it. But there is always a slight out of sync.
