master-server/deps/curl/docs/cmdline-opts/proxy-http2.md

c	SPDX-License-Identifier	Long	Tags	Protocols	Added	Mutexed	Requires	Help	Category	Multi	See-also	Example
Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.	curl	proxy-http2	Versions HTTP/2	HTTP	8.1.0		HTTP/2	Use HTTP/2 with HTTPS proxy	http proxy	boolean	proxy	--proxy-http2 -x proxy $URL

--proxy-http2

Negotiate HTTP/2 with an HTTPS proxy. The proxy might still only offer HTTP/1 and then curl sticks to using that version.

This has no effect for any other kinds of proxies.