MERN app says "Not Found" when deployed to Heroku

I was able to find out that this is a 400 type error. I tried heroku restart, and checking the link to the site. I also cleared out my caches. I would’ve thought that it was size of the file, but this site was working before. I needed to redesign it though and that’s when things started going wrong

The Heroku Logs state the following.

2022-09-08T17:06:25.024953+00:00 app[web.1]: 
2022-09-08T17:06:25.024965+00:00 app[web.1]: > nodeportfolio@1.0.0 start
2022-09-08T17:06:25.024965+00:00 app[web.1]: > node index.js
2022-09-08T17:06:25.024965+00:00 app[web.1]: 
2022-09-08T17:06:25.633907+00:00 app[web.1]: server is listening on port 21681...
2022-09-08T17:06:26.005092+00:00 heroku[web.1]: State changed from starting to up
2022-09-08T17:06:27.749637+00:00 heroku[router]: at=info method=GET path="/" request_id=865d7b78-1e6a-4ff2-8d68-83426a78b6fb fwd="" dyno=web.1 connect=0ms service=6ms status=400 bytes=216 protocol=https
2022-09-08T17:06:28.109650+00:00 heroku[router]: at=info method=GET path="/favicon.ico" request_id=8ba52dc8-9da3-4c69-b7a6-9ddbe77b334d fwd="" dyno=web.1 connect=0ms service=2ms status=400 bytes=216 protocol=https
2022-09-08T17:06:31.861393+00:00 heroku[router]: at=info method=GET path="/" request_id=77371786-4591-4359-8425-bb66cd398ce6 fwd="" dyno=web.1 connect=0ms service=1ms status=400 bytes=216 protocol=https
2022-09-08T17:06:31.915219+00:00 heroku[router]: at=info method=GET path="/favicon.ico" request_id=ec144896-4eed-42b1-a15b-a594205ff9c9 fwd="" dyno=web.1 connect=0ms service=2ms status=400 bytes=216 protocol=https

This is the link to my GitHub