Amazon SNS pending confirm (Mautic 4.0)

Your software
My Mautic version is: 4.0
My PHP version is: 7.4.33
My Database type and version is: Mariadb

Your problem
My problem is:
I am trying to add SNS subscription in AWS but once I create the subscription in AWS it just keeps saying “pending confirmation” and never gets the confirmation.

These errors are showing in the log:

Steps I have tried to fix the problem:
I have followed the instructions and added confirmation endpoints as:
https://(my installation URL)/mautic/index.php/mailer/amazon/callback
as well as
https://(my installation URL)/mautic/index.php/mailer/callback

But none of these approaches worked.

Any idea what I might be doing wrong?