GET {url localhost } net::ERR_SSL_PROTOCOL_ERROR problem with my custom api

I develop an api with a partner. This one if you want to check..
https://github.com/korodum/TrainingAppBack

When I try to connect to this endpoint. I get this error.

ListTrainings.js:19
GET https://localhost:4000/trainings net::ERR_SSL_PROTOCOL_ERROR

The fetch is fine, as is the endpoint.

const [token] = useToken();
  const [ trainings, setTrainings] = useState();

  const [error, setError] = useState();
  const [success, setSuccess] = useState();
  const [loading, setLoading] = useState();
  
  const getTrainings = async () =>{

    try {
      
      setLoading(true);

      const res = await fetch('https://localhost:4000/trainings',{
        method:'GET',
        headers:{
          Authorization: token,
        }

      });
      console.log('RES', res);
      const body = res.json();

      if(body.status==='error') setError(body.message);
      else setTrainings(body.data.trainings);


    } catch (error) {
      console.error(error)
      setError(error.message)
    }finally{
      setLoading(false)
    }
  }

In postman….

>Solution :

You can’t get data through an insecure connection (http) from a secure connection (https)

Change the API Link like the following.

http://localhost:4000/trainings