My page looks like it is redirecting to a URL with a trailing /, Why?

As products exist within a category, such as /brands, such as /brands/my-brand, then /brands/ is a directory.

Or another way to look at it is if there is a URL under the parent URL then it will be a folder, and the default web server logic is to enter the folder if it's a folder.  This cannot be overriden.

The default (and only) behaviour of a web browser is to redirect from /brands to /brands/ because of this.