If you are using Google's email, you can log in using either method.
To make it work, ensure that both emails are identical.
If you enter your Gmail address with a capital letter but connect your Google account with all lowercase letters in the email, the merge will not occur.
Instead, you will become confused between your accounts and may also confuse the support team.
If you initially registered via email and password but then attempt to log in with a Google account, the system will retrieve the user.
If you initially registered using a Google account, please use the same email address associated with your Google account to register and create a password.