When you generate the server side explicit flow, it looks something like this:

https://api.instagram.com/oauth/authorize/?client_id=CLIENT-...

Depending on the library you use, it may be default to response_type=code. Just get the URL and do a search and replace if the library doesn't allow you to define the type.

See https://www.instagram.com/developer/authentication/

I use this library: https://github.com/jaredhanson/passport-oauth2

Something tells me however that just changing it to 'token' (file strategy.js, line 217) actually fixes it, now there are other issues with many redirects when just changing that line, Im not entirely sure how that library works to fix anything else at this point, do you know when this issue might be resolved as a whole?

Unfortunately, Instagram is terrible with responding to developer support tickets and there really isn't a much of a community aspect around it. This issue itself is not easily reproducible. The same account may work on one site and not a another site.