US-East-1 is more than just a normal region. It also provides the backbone for other services, including those in other regions. Thus simply being in another region doesn’t protect you from the consistent us-east-1 shenanigans.

AWS doesn’t talk about that much publicly, but if you press them they will admit in private that there are some pretty nasty single points of failure in the design of AWS that can materialize if us-east-1 has an issue. Most people would say that means AWS isn’t truly multi-region in some areas.

Not entirely clear yet if those single points of failure were at play here, but risk mitigation isn’t as simple as just “don’t use us-east-1” or “deploy in multiple regions with load balancing failover.”