Thanks for the additional context! I’m afraid this is going to be hard to help you with here given your site is private. If you moved to our hosting our support team would be able to log in and take a look. On self-hosting, you could post to Marketplace to ask for help.
Personally I don’t find that stat to be worth looking at on a private site. Maybe you just ignore it if you are not finding your site otherwise affected.
That said, it is pretty strange that a private forum would have many links showing up for that stat. On my personal forum it looks like the below. I think it means one of my siblings has bookmarked the topic?
Is there a chance your members are bookmarking some topics directly? Or do you have another site that includes bookmarks or a feed of some kind linking to topics on your site?