Syncthing syncs when not on my home netowrk

I noticed today that syncthing was successfully moving files from my CasaOS server to my laptop while I was away from home and not connected to the same network as my server. But the web UI and apps do not load. I’m not connected to a VPN or anything fancy.

Should this be possible? I thought you couldn’t access anything on CasaOS without being connected to the same network. Is Syncthing somehow an exception?