Isn't the referral link only on the ad results, which is clearly marked "AD"? That's what my quick test shows.
On LibreWolf browser,
On mouse hover, the correct result urls show but then I right-click one, it shows something like:
https://duckduckgo.com/l/?uddg=<destination_url_here>¬rut...
But this same behaviour cannot be observed on Google/Searx on the same browser. It also even isn't observable with DDG on a FF nightly build on the same system and a FF stable build on a separate one.
Edit: url formatting
EDIT2: this behaviour seems to be limited to my particular setup and even a clean LibreWolf profile seems not to suffer from this issue. I apologise for the misunderstanding.