Hit me. I use syncthing on default settongs to sync my photos from my CalyxOS phone to my Linux PC. No need for central cloud storage service.
Discussion
With default settings you are using syncthing's default Discovery Server for peer discovery and NAT transversal.
Using it will leak network metadata to syncthing org.
You would be better off Disabling NAT transversal and Global Discovery and just syncing on your local discovery. It will only work on your LAN but the tradeoff is worth it IMO.