im having many issues with my backend flask API with CORS. I have done everything which flask documentation and stackover flow says, but I still get this error. Even with cors enabled. Anyone know what is wrong?

Even adding the flask decorator for cross_origin doesn't resolve the issues

from flask import Flask, render_template, request, session, redirect, jsonify, abort
from flask_cors import CORS

import pymongo
from config import get_env_var
from utils import get_token, get_user_information

app = Flask(__name__)
CORS(app)

@app.route("/oauth/discord", methods=["POST"])
def oauth():

Access to XMLHttpRequest at 'http://127.0.0.1:5000/oauth/callback' from origin 'http://127.0.0.1:3000' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: It does not have HTTP ok status.