This is second-hand, so take it with a grain of salt, but I've seen mention of a bug that sometimes causes the same graphql query to be executed in an infinite loop (presumably they're async requests, so the browser wouldn't lock and the user wouldn't even notice).

So they may essentially be getting DDOS'd by their own users due to a bug on their end.

Edit: better info: https://sfba.social/@sysop408/110639435788921057