If multiple services are affected, it's probably some underlying infrastructure issue.

It could prevent Google from rotating in new instances, because they aren't able to obtain a certificate.

Although, if that is the case, I would expect to to impact basically every google site.

Google uses mTLS for communications between systems and it could just be bad timing.

Yeah companies which also operate CAs can print as many certs as they want so it’s tempting to use a bunch everywhere with very short expiry.