Getting SignatureDoesNotMatch errors with AWS signatures

I’m trying to send a POST request that sends a message payload to an SQS queue.
I’ve also included a pre-request script. I have added my secret keys and AWS keys.

When I try to send a request, I get a 400 bad request due to bad syntax.

When I try to run the generated curl code from postman on my terminal I get the following error messages:

SignatureDoesNotMatchThe request signature we calculated does not match the signature you provided. Check your AWS Secret Access Key and signing method. Consult the service documentation for details.

The weird thing is that I’ve never encountered this issue before, and I suddenly started getting these error messages.