Sure, but the comment is so vague I’m skeptical the OP knew what they were doing in the first place, or it happened exactly as they wrote. Maybe a service quota was reset to the default? But just set to zero? Doesn’t pass the sniff test.

"... and they're paying for it..." - that might be the exact issue. Google has no way to ensure that these small shops and startups will pay their bill, so quotas are used to prevent the company from running up a large bill they won't be able to pay.

I see a bunch of threads on reddit about startups accidentally going way over budget and then asking for credits back.

This doesn't at all mean the startups have bad intent, but things happen and Google doesn't want to deal with a huge collection issue.

If someone rolled up to your gas station and wanted to pump 10,000 gallons of gas but only pay you next month - would you allow it?

Well that is kind of a problem of their own making. The clouds refuse to entertain the prospect of pre-paying for services/having some sort of hard spending limits because they know that over-allocation is probably driving a decent amount of revenue.

Are you sure you're not thinking of billing alerts? AFAIK there is still no way to set spending limits at GCP.

I'll admit it's a bit obscure But there is info here.

https://docs.cloud.google.com/apis/docs/capping-api-usage

Or you can do it programmatically.

https://docs.cloud.google.com/billing/docs/how-to/disable-bi...

That’s not how quotas work in GCP. Google sets quotas for certain APIs for interacting with GCP itself, like how many VMs you can create per second. They’re not billable. Sometimes these quotas can be be increased if you need them to be. But the way op described it makes no sense.