Yeah, the link feature has been there as as long as I can remember, and it works as expected.
i.e. it gives the link (the URL) of the specified page and database entry - which is a text.
As @Jici pointed out, you’re trying to send a datatype to a page, so you don’t want to use the link feature there - just define the datatype entry (the specific thing from the database).
The link feature is to get the actual link to the page for the specific datatype, as in the actual URL. e.g.
www.mysite.com/mypage/mything, so that will evaluate to a text.
You can use it to display the link, or to open an external URL, or for use in API calls, emails, etc. but for sending data to a page, just select the datatype ‘thing’ directly.