Is there any safety switch to prevent the situation like unmounted/unavailable directory causing this behavior? Maybe if the entire repo disappears Syncthing shouldn’t instantly propagate the change but ask the user first? Or make it a per repo option. Some directories for temprorary file exchange may become empty often just because the files come and go. And some with important data should be protected from this.
Besides, there’s always a directory named .stfolder (probably not on Android though), I suppose if it disappears Syncthing considers this an error and doesn’t wipe out the contents on the other side? Anyway, an option to protect against such accidental wipes would be very nice to have.