Add 4740180 to the list of silly magic numbers
Oh dear. The software fungus where bits of code take the literal characters "HTTP" as a number has expanded. Now it has a variant: 4740180.
What's that? 4740180 is 0x485454... that's "HTT".
Where does this one come from? Go and gRPC, apparently!
Again, it comes down to "HTTP/1.1 400 Bad Request" being parsed as part of some binary protocol.
I found this while searching the web for "1213486160" to see how things have been going in the past few years. Unfortunately, it's still biting people all over the place. There are far too many posts asking people to upgrade their software, or restart things, or do any number of useless rubber-chicken-waving techniques which ultimately will accomplish nothing.
When you see a funny-looking number, figure out where it comes from. That's the only way to have any chance of understanding what's actually going on.