> I was pretty geared up to have a contrarian opinion until I looked at the standards but they're actually pretty clear, a 404 could be a proper response to unexpected query string; query string is as much part of the URL API as the path is and I think pretty much everyone can acknowledge that just tacking random stuff onto the path would be ill advised and undefined behavior.

This feels like a technically correct is the best kind of correct situation. Like technically, yeah web servers may respond 404 if they dont understand a query parameter, but in practise that is not how urls are conceptualized normally.