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.

On Android:

Go to Setting in Google Authenticator

Select Time correction for codes

Click on Sync Now

On iOS

Go to Apple iPhone setting

Select General

Select Date & Time

Enable Set Automatically

In case, Its already enabled, disable and re enable it after few seconds.