I recently noticed while debugging an app that my not-found.jsx file was running every route (even if it was a valid route). I thought at first it may be something specific to my setup since I use a catch all dynamic route for the entire website, however, I think it has to do with NextJS itself.

I created a new project with create-next-app. I then added a not-found.jsx file along with console.log statements in the home page and the 404 page. If you go to the home page, you will notice both console.log statements run.

Why is that? Is the 404 page always ran in case something doens't resolve and NextJS can quickly swap that route in??