Is there a way to dig deeper into a AWS Cloudwatch error for where "Access Denied" is failing – Amazon Web Sevices

I am working on a snippet of code that interacts with an API call to my AWS instance for cognito, it runs the following snippet:

public function getCognitoIDPSettings(LoggerInterface $logger, string $cognitoCustomerUserpoolIDP): array
{
    $body = json_encode([
        'cognito_customer_user_pool_idp_id' => $cognitoCustomerUserpoolIDP,
    ]);

    $url = COGNITO_API_INVOKE_URL . '/idp/get';

    $response = $this->postFunction($logger, $url, $body, 'application/json');

    $this->checkResponseStatus($response);

    $body = json_decode($response->getContent(), true);
    if (JSON_ERROR_NONE !== json_last_error()) {
        throw new JsonException("failed decoding response from cognito api");
    }

    return $body;
}

When it is hitting the:

$response = $this->postFunction($logger, $url, $body, 'application/json');

It is erroring with:

Error: "Got an error from API: u0027{u0022messageu0022: u0022Internal server erroru0022}u0027 with error code 0"
File: /var/www/billing/src/Domain/Auth/CognitoAPIFacade.php
Line: 398

This error isn’t very indicative so I jumped into the Cloudwatch and found:

I can see it’s an "Access Denied" error but I want to dig deeper into where this is occurring or if there’s a way I can best further diagnose this, any ideas of people facing a similar problem and can provide some useful guidance?