If anything important ran on Google Cloud, you can bet we'd see a blog post from Google Cloud marketing about that. Yes, many of the money losing side bets from the non-Google companies under the Alphabet umbrella use Google Cloud. That's only because they want the optionality to spin them off if by some miracle any of them are ever worth anything. If they were part of Google, they would use internal infrastructure. If they weren't under Alphabet, they would use AWS or Azure like everyone else.