It seems like Google is now showing multiple referring pages for some URLs in the URL Inspection Tool within Google Search Console. Amy @amy91485 noticed it and Glenn Gabe thinks it is new as well. I spotted up to four different referring pages in this tool now.
Here is what it looks like (click to enlarge):
Here are those tweets:
Hey, thank you! I'm glad you found the cases helpful. They were super-interesting to work on.
— Glenn Gabe (@glenngabe) January 15, 2021
And I think you're right... I saw that today and didn't really think about it. But I don't remember seeing multiple referring urls there before. I'll double check some things now. pic.twitter.com/WDqjFd3dt3
Of course, there can be tons and tons of referring pages to a specific URL on your site. A referring page is the page that Google uses to discover the URL.
A referring page according to Google's help documents is:
A page that Google possibly used to discover this URL. The referring page might directly link to this URL, or it might be a grandparent or great-grandparent of a page that links to this URL. If this value is absent it doesn't mean that no referring page exists, just that this information might not be available to the URL Inspection tool at this time. If you see "URL might be known from other sources that are currently not reported", it means that Google found this URL through some means other than a sitemap or referring page, but the referring information currently isn't available to this tool.
So Google can show you not one singular way it discovered the URL but multiple.
In my example above, you can see Google is saying it discovered this page from two of my RSS feed URLs and then two other web page URLs on this site. Most of time time, at least for new pages, you see "None detected." But if you wait long enough, Google can now show you multiple referring pages here.
Update: Daniel Waisberg from Google confirmed it is new:
Yep, that was released as part of the Index Coverage update earlier this week . Enjoy! 🎁
— Daniel Waisberg (@danielwaisberg) January 15, 2021
Forum discussion at Twitter.