Doesn't /3 mean v3? I mean, for HTTP itself, doesn't the HTTP/3 == HTTPv3? If so, I don't see how this is any better than SSH3 - both SSH3 and SSH/3 read to me like "SSH v3"
Yes, but HTTP is about the only thing that versions with a slash. By writing it SSH/3, it would emphasize its relationship with HTTP/3, instead of it being the third version of SSH.