This is a bit of a long shot and depends on the performance of future quic-go releases but QUIC already tends to perform better on high latency connections:

https://forum.syncthing.net/t/prefer-quic-option/19136

https://www.reddit.com/r/Syncthing/comments/ye0429/syncthing_quicserver_quickclient_disconnecting/

Seems like quic-go v0.30.0 already comes with a bunch of performance improvements and batch writing is scheduled for v0.31.0.

Once quic-go is able to saturate a gigabit link, we should change the priority for WAN connections.

As for LAN i don't see any benefits because packetloss and latency is not an issue here.