UPDATE: Netlify are actively monitoring but suggest all impacted sites have recovered.

All of our e2e tests and monitoring suggest y.co has recovered.

The issue has been found and the hosting provider is rolling out a fix across the Standard Edge Network and sites are recovering. This work is still in progress.

Some users may experience a blank screen. This is due to an issue with the hosting service and their caching network. We are monitoring their updates and will update once we have more information.
Sorry for any inconvenience