Hypixel.net is both their website and mc server adress.
Is it just that https is on port 443 and minecraft is on port 25565?
And if that is the case, can i do something similar by making a reverse proxy have two seperate server blocks for the one domain, with different ports?
TCP and UDP can listen on the same port, DNS is a great example of such. You’d generally need it to be part of the same process as ports are generally bound to the same process
They don’t even need to be the same process. I’m pretty sure that’s just a common practice if something needs both protocols, but there’s nothing stopping you from having a web server on TCP 443 and a VPN server on UDP 443. Ports are an abstraction brought by each protocol, they aren’t in anyway related.