Few developers ported to Stadia out of good will, Google paid very handsomely up front.

Yeah, this. My previous company got paid a lot of money to bring our titles to Stadia. And it wasn't worth it, as Google kept changing APIs and interfaces. And then nobody played the game. It didn't happen again, and basically everyone in this industry has been using Stadia as a punchline for years.

Not the developers who google poured millions into to have them port games to stadia.

Porting games? Isn't it essentially and RDP connection?

Nope, it ran on specific hardware and needed specific compilation. It definitely wasn't free to support.