Thank you very much @John_Page for narrowing the issue and sharing your knowledge.
Yes, using the deprecated built-in SES client solved the issue and I already changed my App to use that for now.
But it will be deprecated on August 1st. What’s the solution going forward? I understand when you said that when calling the SES endpoint the Request is using ISO8859-1. But how to overcome this?
Note:
— I’ve tried both AWS SDK JS v2 and v3, both have the same issue. Is this an App Service’s Dependency issue?
— Sorry for saying again, but I used to send emails just fine using the solution I shared above (with AWS SDK v3 as dependency with @aws-sdk/client-sesv2 package) why suddenly it stoped working?
Thank you very much again.