Why is FedEx API returning encoded characters?

FedEx Address Validation API is returning encoded characters and a 400 bad request error. Here is my request body with the secret key blocked out for obvious reasons:

POST /address/v1/addresses/resolve HTTP/1.1Content-Type: application/jsonx-customer-transaction-id: x-locale: en_USauthorization: Bearer {my secret key}{"addressesToValidate": [   {"address":{"streetLines":["1234 Example Rd.",""         ],"city":"Morris","stateOrProvinceCode":"AL","postalCode":"35116","countryCode":"US"      }   }]}

This is what the encoded response looks like:

HTTP/1.1 400 BadRequestContent-Type: application/json;charset=UTF-8Content-Encoding: gzipConnection: closeServer-Timing: cdn-cache; desc=MISS,edge; dur=115,origin; dur=62Content-Length: 175Date: Tue, 28 Jun 2022 18:47:56 GMTServer: Layer7-API-Gateway�ʱ�0�_��l�a�Ƞ���p�6�6�@B�������;2�d���+�)�$�4�B%b�L�3W"�%�N�L��9�<���U9n7��,���REY����{j�Z�=��í�A��Z�8�L���J�Lvp��=���M@i������ϱ

Here is the API documentation for reference: https://developer.fedex.com/api/en-us/catalog/address-validation/v1/docs.html#operation/Validate%20Address