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. 
If for any reason, this is not desired, the options are to not use substrings of URLS that are nested and instead something like:

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