NextJS deployed to Vercel: 404 page not found

I have a NextJS app without an integrated api that I want to deploy to Vercel. It works fine when I run it locally yarn run dev and I can also build it yarn run build without any errors. When I deploy it Vercel, however, I receive a 404 Error.

Here is my folder structure:

app/
  - components
  - pages
    - editor
      - [id].tsx
    ...tsx
  - public
  - utils
    - db
      api.ts

I am using NextJs 10.0.3.

Here is a link to the deployed app.

I don't have a nextjs config file. My assumption is that the error is caused by the dynamic route but I can't find my mistake. Also, no page is working when the app is deployed as opposed to only the dynamic page.

Do you have pointers on where to look next?

EDIT 1:
Here is a link to the GitHub repo.

EDIT 2: I found an issue but don't know how to fix it.

This is how my build output looks like on Vercel:

This is how it's supposed to look like on Vercel:

Not sure why the whole _next folder is missing.

Go to Project Settings

Change Framework preset from Other to Next.js

Redeploy the project.