Undertstanding tailscale ports

I’m trying to understand what ports tailscale requires to function.
Looking at the knowledge base What firewall ports should I open to use Tailscale? · Tailscale I can see that multiple ports should be allowed to be opened, however testing locally I only opened port 443 outbound and tailscale worked without the need for the other ports and not using the derp relays.
I’m confused by this so any clarification on this would be great!