It was unclear to me that you were being tongue-in-cheek. Were you serious, I'd point out for starters that A. You probably don't know whether it's serverless currently and B. Even if it were it's not a particularly uniquely likely explanation for consistent latency at scale
my understanding is that in a serverless architecture the dev does not manage the server, there still is one but its managed via third party cloud services who expose basic server or database functions which your app can plug into.
think a "like count" database, it needs to increment and persist. Both very simple, and its implementation is entirely decoupled from the client implementation. Firebase would manage that for you, youd just call firebase functions instead of updating a database yourself.