This may be of some help :
https://gitlab.com/librewolf-community/browser/common/-/issues/54
# librewolf.overrides.cfg ($HOME)
lockPref("identity.sync.tokenserver.uri", "https://token.services.mozilla.com/1.0/sync/1.5");
lockPref("extensions.getAddons.langpacks.url", "https://services.addons.mozilla.org/api/v3/addons/language-tools/?app=firefox&type=language&appversion=%VERSION%");
lockPref("signon.rememberSignons", true);
lockPref("browser.tabs.loadBookmarksInTabs", false);
lockPref("general.autoScroll", true);
# policies.json (Installation/root)
DisableFirefoxAccounts: false