I’m unfamiliar with codesandbox, but even if you’re using a “no/low code” solution, it’s ultimately still a React based site (as it says in the title tag):
So it’s still getting built somewhere along the line, even if you aren’t the one that has explicitly configured the command being run.
Your PDF file was in the location linked when I posted, but I’d hazard a guess that you’ve done another deployment and you’ve either removed the file, or the hash generated against it has changed from e50393ac to something else.
I still have the file open in my browser at the location your previous build log mentioned…
Whatever the issue is, it’s not a Netlify one, it’s down to your build, (even if you aren’t the one setting it up entirely), you need to ensure that it’s configured in a way where the file ends up where you expect it to end up.