I faced the same issue, especially with timeout error after providing the tailscale ip as "tcp://<ip4-address>:22000". I'm not sure how to resolve this and any help on this will be appreciated.
I wish I could help you, but I couldn't get Syncthing to start up so I ended up clearing the app storage and set up the devices and folder shares again. It wasn't too bad. If you have a backup you could try restoring from that in settings. I tried changing the IP back in config.xml but I couldn't browse to the file location using my file browsing app and gave up.