Does anyone on the inside know, when people talk about login services being down, what’s the actual technical bottleneck?

I’d hope we’re not talking about them simply not having enough CPU to bcrypt_compare() everyone’s passwords as they try to log in…

In-house service-wide rate limits that are too low?

Two-factor auth steps? (Third party providers may be rate limiting?)

Anti-fraud things? GeoIP lookups? Etc

Writing out logs of logins? Some login audit DB?

(Or is it not actually some login-specific service that is down?)