In .NET 5 for an HTTP/1.1 request, SocketsHttpHandler would typically end up allocating two async state machines for a total of 480 bytes:

In .NET 6 for the same request, it now typically ends up allocating five async state machines for a total of 952 bytes:

(These traces are for ~10K requests).

The extra state machines come from the DetermineVersionAndSendAsync, SendUsingHttp11Async, and SendAndProcessAltSvcAsync async methods.