The only way to get SLA credits is requesting it. This is very disappointing.
SLA CREDITS
If you believe your paid application experienced an SLA violation
as a result of this incident, please populate the SLA credit request:
https://support.google.com/cloud/contact/cloud_platform_sla
SLACreditRequestsAAS? Who's with me, all I need is a co-founder and an eight million dollar series A round to last long enough that a cloud provider buys us up before they actually have to pay out a request!