For the last decade or so I get a second $0.85 monthly bill from google. Nobody at google knows why, but they recommend to leave it because who knows what could be disabled if I block those payments. Interesting detail here is that this is on a bank account that we stopped using in 2017, so the only reason we are keeping that account alive is for these stupid google payments. In the cloud environment there is an invoice for the amounts, but no way to change the billing info to our current account and also no way (not by us, not by google support) to figure out what these payments are actually for...

Calling it kafkaesque is giving it too much credit.

I recently got an email saying a project I got is at the risk of being disabled because my payment information is invalid. But the card I got registered for it is the same I've had the last two years, and it's still valid cause I used it yesterday. Also, there is no amount due as far as I can tell. I haven't done anything with the project for 6 month, it's just sitting there. No API usage, nothing.

So I got no idea what to do to address it. I feel my best option is wait for it to get disabled and try to address it afterwards.

Chargebacks or disputes will lock your account, so definitely stay away from that path.

But just closing the bank account will stop auto billing (it's considered a decline). So if you closed the account, it would just stop paying for whatever it is, and then cloud may lock the gcp account until it's paid. (I'm not 100% sure what cloud does with unpaid invoices).