CORS with Flask, axios and https not working (response header sends origin as http instead of https) - react-native

Question

My frontend (Expo Go web) is running at http://localhost:19006/ but when it receives a response from the backend, it somehow believes it runs under https://localhost:19006/
Also, the iOS version of Expo Go logs the following error:
LOG [AxiosError: Network Error]
I'm using Flask in the backend with CORS set as follows:
app = Flask(__name__)
app.config['DEBUG'] = True
app.config['CORS_HEADERS'] = 'Content-Type'
app.config['SECRET_KEY'] = os.environ.get("SECRET_KEY", 'xxx')
cors = CORS(app, resources={r"/*": {"origins": "*", "allow_headers": "*", "expose_headers": "*", "Access-Control-Allow-Origin": "*"}})
and a simple return function:
#app.route("/matches", methods=["GET"])
def getMatches():
print('request for matches')
response = matches.getMatches()
return response
if __name__ == '__main__':
app.run(ssl_context=('certs/cert.pem', 'certs/key.pem'))
My frontend part is using react native with Expo Go. The query to the backend is done this way:
export default function App() {
const axiosApiCall = () => {
const config = {
headers:{
'origin': 'https://localhost:19006' #<- Here also tried http but no change
}
};
axios
.get("https://127.0.0.1:5000/matches", config)
.then((response) => {
setState({quote : 'yes'});
console.log(response.data);
})
.catch((error) => {
console.log(error);
})
}
The backend works properly fine as I can see in Postman. The result is technically showing up in the response of the web-version of Expo Go, however, it appears that there's an issue with CORS:
Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://127.0.0.1:5000/matches. (Reason: CORS header ‘Access-Control-Allow-Origin’ does not match ‘https://localhost:19006’).
And here's the response header:
HTTP/1.1 200 OK
Server: Werkzeug/2.2.2 Python/3.9.16
Date: Thu, 05 Jan 2023 10:16:42 GMT
Content-Type: application/json
Content-Length: 274552
Access-Control-Allow-Origin: http://localhost:19006
Access-Control-Expose-Headers: *
Vary: Origin
Connection: close
GET /matches HTTP/1.1
Host: 127.0.0.1:5000
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:108.0) Gecko/20100101 Firefox/108.0
Accept: application/json, text/plain, */*
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate, br
Origin: http://localhost:19006
DNT: 1
Connection: keep-alive
Referer: http://localhost:19006/
Sec-Fetch-Dest: empty
Sec-Fetch-Mode: cors
Sec-Fetch-Site: cross-site
Sec-GPC: 1
Anyone any idea? Thanks!!!
Hardcoding the CORS origins: no change
Changing the query from axios to async fetch calls: no change
Including/modifying the header in the axios config: no change
Other browsers: no change
Deactivating SSL in the backend: caused other problems related to react native