HTTP status codes: the passive-aggressive notes of the internet. Top panel shows the server handing over a nice "200 OK" response to the client. Everything's working, life is good.
Bottom panel? Client's getting a "400 Bad Request" error, complete with that JSON error object that might as well say "it's not me, it's you."
The client's face says it all - that unique mixture of confusion, rage, and existential dread that hits when your request fails but you're absolutely certain your syntax was perfect. Spoiler: it wasn't.