The Content-Type request header describes the type of the body so when there is no body (e.g. a GET request) the Content-Type header is inappropriate and leads to CORS issues since Content-Type: application/json prevents a request from being "simple": https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS#simple_requests
The Content-Type request header describes the type of the body so when there is no body (e.g. a GET request) the Content-Type header is inappropriate and leads to CORS issues since
Content-Type: application/json
prevents a request from being "simple": https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS#simple_requests