IncorrectSignature on BeanstalkDeployApplication task with AWS Service connection

**Describe the bug**

I am trying to deploy to Beanstalk using the Service connection using IAM user with AWSElasticBeanstalkFullAccess set up. The problem occurs when the task starts.

**To reproduce**

Try to deploy the .net core app to Beanstalk using the BeanstalkDeployApplication@1 task and configured AWS service connection.

the output of the task:
`Deployment type set to aspnetCoreWindows
Configuring credentials for task
...configuring AWS credentials from service endpoint '8b05c70e-f688-410c-a86d-2344d08e7dbb'
...endpoint defines standard access/secret key credentials
Configuring region for task
...configured to use region eu-central-1, defined in task.
Configuring credentials for task
...configuring AWS credentials from service endpoint '8b05c70e-f688-410c-a86d-2344d08e7dbb'
...endpoint defines standard access/secret key credentials
Configuring region for task
...configured to use region eu-central-1, defined in task.
DescribeApplications: error aligator returned querying for existence of application IncompleteSignature: 'AKIARJ2YL6ASDSPAUCGR/20200906/eu-central-1/elasticbeanstalk/aws4_request' not a valid key=value pair (missing equal-sign) in Authorization header: 'AWS4-HMAC-SHA256 Credential=***/20200906/eu-central-1/elasticbeanstalk/aws4_request, SignedHeaders=host;x-amz-content-sha256;x-amz-date, Signature=b5082855ee95696c69fac9e85a48b3871949d67bc1ee31b05d56f61790ddca2a'.
##[error]Error: Application aligator does not exist
Finishing: BeanstalkDeployApplication`

**Expected behavior**

Task works.

**Screenshots**

The tasks configuration used:

the application and the environment are present in Beanstalk:

**Your Environment**

- On-prem or cloud based?: cloud based
- Azure DevOps version: lastest
- AWS Toolkit for Azure DevOps version: lastest

**Additional context**

I also tried changing the policies the configured IAM user has attached to what's below but no luck.

Start with the BeanstalkDeployApplication@1 task and reproduce the deployment using the AWS service connection, eu-central-1 region, and the configuration described in the issue. Trace the credential and request-signing flow around the IncompleteSignature response; done means the existing Beanstalk application is found and deployment proceeds without the malformed Authorization header error.

Written by the indexing model from the issue text.