What's a virtual interface and why does it keep getting added to my wifi connection

Hello,

I keep noticing that a network bridge (please correct me if I'm wrong) keeps getting added on to my network interface Via here:

In this instance it's my Wi-Fi, sometimes I use a VPN and it attaches itself to that too:

If I click that I see:

I only use the thunderbolt ports for power and use a router for internet....

I'll delete it after noticing it sometime after startup and then, usually after a restart/shutdown, it returns, I've tried deleting/reloading the network config plists and it doesn't change anything.

Some help would be majorly appreciated as I equally don't want to be disabling something my mac relies on.

Thanks