Social Connection "redirect_uri=" query string starts with & instead of?

I’m working on a custom social connection for one of our partners. I’ve configured everything in the social connections settings and am in the process of testing that connection. I’m noticing that, when the user is sent to log in using the Authorization URL, the URL they are sent to looks like this:

http://example-auth.com/?prompt=login&response_type=code**&redirect_uri=https:%2F%2Fexample.auth0.com%2Flogin%2Fcallback&state=xvqYddEmcUIy4ablpsH3Un_3nH6aS30D&client_id=84c623fc82c7416ca7c31e7b01001d45%20%20%20**

The issue here is in the redirect_uri parameter. Within that parameter there is another URL but it is formatted incorrecttly. Where the query string for that redirect_uri is supposed to start - there is an & iinstead of a ?.

My question - is that & an indication that this is a new query string parameter within the outer URL? (the initial authorization URL) or is this an error where it is instead supposed to be a URL encoded ?