If you want to check if a particular request is done over HTTP/2, I'd recommend to use the is_http2 property:
https://docs.mitmproxy.org/stable/api/mitmproxy/http.html#Message.is_http2

It's true that the protocol is commonly referred to as HTTP/2 and not HTTP/2.0. At the same time, I don't think you can argue that either is wrong. If you look at the RFC, you see that it only really defines "h2":
https://datatracker.ietf.org/doc/html/rfc9113#name-http-2-version-identificati
and that the preamble uses in fact "HTTP/2.0":
https://datatracker.ietf.org/doc/html/rfc9113#section-3.4

That being said, considering we use HTTP/3 for HTTP/3, I guess I'd be willing to merge a PR that changes it to HTTP/2 everywhere. :)

Aite, sure @mhils. I'll do a PR anytime soon.

FYI, while HTTP/2 was initially developed under the working title of HTTP/2.0, the final, official name adopted after the standardization process was simply HTTP/2.

p.s. h2 is an abbreviation of HTTP/2 stated in the document.