identity.sync.tokenserver.uri in the about:config can be edited but after a restart of the browser the original uri is sitll intact.
Also I can create an account @ https://ffsync.garudalinux.org/1.0/sync/1.5 and sign in. However after signing in the menu is still asking me to sign in.
I think that the uri should read https://ffsync.garudalinux.org/token/1.0/sync/1.5 according to the documentation.
Thanks I added lockPref("identity.sync.tokenserver.uri", "https://token.services.mozilla.com/1.0/sync/1.5"); to firedragon.overrides.cfg, and restarted the firedragon browser. When I got into about:config the uri has not changed.
You just helped finding a really annoying bugs solution! I was searching for why this seemed to happen for some people (it didn’t happen to me for some reason?!), just got the confirmation that this was indeed the issue. Guess that means bye bye ClearURLs