Hi, using your Google account to sign in on other sites requires cross-site data sharing. It's possible that privacy features such as tracker blocking, cookie blocking, or containers is preventing the cross-site data sharing. However, it's difficult to guess which one it might be. '''Firefox's Enhanced Tracking Protection feature''' The shield icon toward the left end of the address bar usually turns a bit purplish when content is blocked. Click the icon to learn more or make an exception. See: [[Enhanced Tracking Protection in Firefox for desktop]]. '''Container Extensions''' You can use Multi-Account Containers and other container extensions to prevent cross-site data sharing between tabs for different sites. If you use one that applies to either the site you are visiting or to Google, this could be the problem. '''Testing in Firefox's Safe Mode''' In its Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, and some other advanced features to help you assess whether these are causing the problem. ''If Firefox is running:'' You can restart Firefox in Safe Mode using either: * "3-bar" menu button > "?" Help > Restart with Add-ons Disabled * (menu bar) Help menu > Restart with Add-ons Disabled and OK the restart. A small dialog should appear. Click "Start in Safe Mode" (''not'' Refresh). ''If Firefox is not running:'' Hold down the Shift key when starting Firefox. (On Mac, hold down the option/alt key instead of the Shift key.) A small dialog should appear. Click "Start in Safe Mode" (''not'' Refresh). Any improvement?