Are there not notifications you can set via billing? And I would assume you could send those messages to a service to autoscale the infra, but maybe that's out of scope
I did set a notification for billing, and I got completely screwed over because credit was actually only applied as a one-time credit and did not cover the costs. I did have warnings to make sure we didn't go over the costs but it's still possible to go over. I can't babysit it.
What we can get for $2000/month from Google Cloud Platform is around $200/month from Hetzner and it would have made more sense to use Hetzner without this credit. It's now completely counterproductive because the amount I've been charged would have gone so much further there.
I'm not interested in every using GCP ever again credit or not unless we get these charges reversed. I can't do a chargeback without risking my whole Google account where I have other important stuff like Google Domains unless I moved that all off their platforms somewhere else.