Google's John Mueller said on Twitter that generally Google will not make up URLs to index on your web site. So if you find weird parameters at the end of the URLs showing up in the Google index for your web site, Google probably found someone linking to that URL. Either you have some pages that link that way or someone on a third-party site does.
You can fix it by either using a 301 redirect from that URL to the canonical URL or by using the canonical tag on the page to the right URL.
Here is John's tweet with the original question:
In general, we wouldn't make up URLs like that, so I imagine we found them as links somewhere. With the normal canonicalization methods you can usually encourage our systems to focus on your preferred URLs.
— 🍌 John 🍌 (@JohnMu) November 25, 2019
Forum discussion at Twitter.
