The most common issue faced with 2FA is :
"Google Authenticator app not being synced correctly"
To make sure that you have the correct time in your Google Authenticator app follow the instructions given below.
Go to Setting in Google Authenticator
Select Time correction for codes
Click on Sync Now
Go to Apple iPhone setting
Select Date & Time
Enable Set Automatically
In case, Its already enabled, disable and re enable it after few seconds.