Sync files (KeePass) between devices (PC, mobile, tablet, RPi)
If I’m not mistake the default settings makes it so syncthing is not peer to peer but it involves their servers to pass the data. If anyone knows more about this please share.
You probably mean the relay servers. They are used in case your devices are behind a NAT and don’t have any ports forwarded. In that case, it would be impossible for devices on different networks to communicate over the internet, so the relay servers make the communication work. It’s not something to worry, since your data is encrypted when passing through it, but it can be disabled.