Is it mandatory to link a phone number to my Petal Mail account during registration and can it be a number that has been used to register a HUAWEI ID?

Your Petal Mail account must be linked to a phone number during registration in case that you forget your password.

The linked phone number is the security phone number, which can only be used for secondary verification and resetting the password but cannot be used to log in to your account.

Therefore, even if the number has been used to register a HUAWEI ID, it can still be used as a security phone number. (Each security phone number can be linked to a maximum of five Petal Mail accounts.)