please have a look at this :
This fix was actually suggested by @BluishHumility
/ Override Firedragon's hardcoded file-picker setting
lockPref("widget.use-xdg-desktop-portal.file-picker", 2);
// Use Mozilla sync servers
lockPref("identity.sync.tokenserver.uri", "https://token.services.mozilla.com/1.0/sync/1.5");
// Restore user-triggered clipboard access
defaultPref("dom.event.clipboardevents.enabled", true);
I just remembered it now, and added it in my .firedragon
I hope this will help