This can happen if there are connection problems with the internet. To ensure that you aren't asked for your password (and 2FA) each time the Launcher app launches on start-up you can start the Launcher manually once your computer has established an internet connection.
To disable the running when Windows boots option in Epic Games Launcher:
- Open the Epic Games launcher.
- Click your profile icon in the upper right corner.
- Select Settings.
- Uncheck the Run When My Computer Starts box.
- Reboot your PC.
- Ensure that your PC is properly connected to the internet (you are able to visit webpages, etc).
- Start the Epic Games Launcher.