The following content is translated using GPT machine translation. Dear Firefox team, I encountered a problem while using the Firefox Sync service. After registering an account with one of my email addresses, I tried to log into this account on another device, but it prompted me to register again. After following the instructions and registering, I found that both Firefox accounts are associated with the same email, but they cannot be linked together. Later, I tried using a different email address, but the same issue occurred. Finally, I attempted to log in with Google, only to discover that one of the devices does not have the option to log in with Google. I suspect this might be the reason why I cannot use Sync. The Firefox version on this device is 128.02, running on Win10. Looking forward to your response. Wishing you a pleasant day.