I think in this explanation there is a wrong screenshot , there is an screenshot of the notification on CodeCommit, not Triggers. You may want to replace that picture
You are hosting your application code on AWS CodeCommit in US East (Ohio) region. You want to be notified when anyone pushes code to the master branch so you have created an AWS SNS topic on the US East (N. Virginia) region, on which your corporate Amazon SES email domain is also hosted. On CodeCommit, you have created a trigger that will publish a message to your SNS topic. However, your CodeCommit trigger is not working as expected. Which of the following is the MOST likely cause of this issue?