You can Ctrl + J to open Chrome's Downloads window and there you can see what is / was the actual link the file was downloaded from.
On the desktop version of Chrome the link is either fully visible or there is an option to copy it I cant recall that detail now. And on mobile version I could just now confirm that the newest firmware binary is still hosted on the same domain: s3.amazonaws.com
So like I said: clicking on that link with amazon.com domain redirects the request to the old known firmware server domain.