This article is .. weird. It mentions SOCKS5, DynamicForwarding and "decent version of nc", while you don't need anything at all for forwarding connection -- SOCKS is not involved in any way, and initial 1995 release of nc would work just fine.

Here is a much better explanation (from [0]):

> ProxyJump was added in OpenSSH 7.3 but is nothing more than a shorthand for using ProxyCommand, as in: "ProxyCommand ssh proxy-host -W %h:%p"

so the same thing that top poster was talking about.

[0] https://superuser.com/questions/1253960/replace-proxyjump-in...