Hi. So I encountered this on catfriend1’s syncthing-android fork originally and already found an answer for this but I am making this forum post for other users in case they encounter the same problem on the official syncthing-android app.
Problem: Web UI is showing an incorrect/different device ID than that of the syncthing-android app.
Fix: Export the configuration and then import it back again. As for the cause I’m not sure what it is.