QUIC offers:
* fast connection establishment (the libp2p handshake completes in 2 RTTs instead of 4-5 RTTs when using TCP)
* enhanced congestion control and loss recovery -> faster transfer / message propagation speeds, especially on lossy connections
* another connection option next to TCP -> better chances of censorship circumvention (makes it harder for networks to block Ethereum traffic)

Since Lighthouse has had QUIC support for ~half a year now (see https://lighthouse-blog.sigmaprime.io/Quic,%20Networking.html), Prysm nodes will now be able to use QUIC to connect to those Lighthouse nodes, as well as to other Prysm nodes.