What is wrong with this HTTPclient request that is always returning HTTP response = 400 (bad request)? - httpclient

Question

I have done some projects with Arduino but is my first with HTTP post request, so forgive me if this is a very basic issue. I have been reading a lot of stuff on the forum/internet but haven't find anything to put me on the right path and therefore any help will be greatly appreciated.
When running the code below, on a AI-Thinker ESP32-CAM board (my end goal is to upload a picture to the service provider), I get always the "400 bad request" error.
Any ideas of what am I doing wrong? Also a suggestion as how to read the response body could be helpful in order to identify/fix the issue
#include <WiFi.h>
#include <HTTPClient.h>
const char* ssid = "SigloXX";
const char* password = "";
void setup() {
Serial.begin(115200);
Serial.setDebugOutput(true);
Serial.println();
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.println("WiFi connected");
WiFiClient client;
HTTPClient http;
// set the server
http.begin(client, "mydomain.org/auth/login");
// set the headers
http.addHeader("accept", "application/json");
http.addHeader("Content-Type", "application/json");
// JSON data to send with HTTP POST
String httpRequestData = "{\"password\": \"myPassword\",\"login\": \"myLogin\"}";
// Send HTTP POST request
int httpResponseCode = http.POST(httpRequestData);
Serial.print("HTTP Response code: ");
Serial.println(httpResponseCode);
// Free resources
http.end();
}
Many thanks in advance