You know there are companies who build crawlers or health check agents exactly for this purpose, so that they know precisely from when to when the service they pay or they need for their business doesn't work and went out of SLA. I think it's brilliant and the only way to make any company pay. I believe you can sometimes get away with a couple of pingdom checks/jobs.

Like they have any bargaining power against Google.

I don't know how it works in such cases, I mean, this is publicly known that there was an outage.

What I believe is that customers will probably get free GCP credits and that's it, everything is good as before.

This person service-provides