Ibthink if route53 was down. Your dns provider whouldn't able to go there. So it will go to the root who will give gcp one too. So your dns provider might try that.
(I don't know if this is how it works, but I thibk that's how it supposed to work)
You typically have four name servers for a domain, but they don’t all have to be hosted with the same company. Very handy when your DNS provider decides to brag they are unhackable and the hackers reply by immediately hacking them followed by DDoSing them to death.
