You’ve never put your own credit card on public cloud, I take it? Random, mysterious charges are practically a sport.

But what if I were to lend my old android tablet to my visiting 4-year-old nephew, and I found they'd used my linked credit card to spend $500 on lootboxes in whalecraft?

Google is pretty famous for their nonexistent customer support, so I can't expect satisfaction there. And a chargeback would risk getting my entire account blocked.

I won't wade into if Google is a scam company, scam companies usually offer a support option they ignore which is more than can be said about google.

You gave them permission to bill for a reason. They decide the reason and amount and you pay. Seems risky without support.