why my vercel in nextjs application not showing anything?

Basically, my problem is that my nextjs application is just a pure blank “gray” page website, and I don’t know why.

I already did the npm run build for building the application of nextjs which the folder will be created in .next right?

And this is what my project looks like in my folder VScode.

enter image description here

And I don’t know why even I already it in my github and then try to deploy it in vercel but it doesn’t work? Can anyone explain me why? Is it have something to with environment?

Note my project is only a CRUD with API that’s it

and as you see its empty here.

and the link is here

https://nextjs-crud-api.vercel.app/

enter image description here