Why does the URL path use dot response 404?

Website, Application, Performance
1

I use Vercel for hosting and Cloudflare for CDN. I have a path like this /a/music.pop. When I access the domain that uses the Vercel CDN, it can be accessed without a 404 error, but when I access the domain that uses the Cloudflare CDN, a 404 error occurs.
Guess why?