B+ according to my DuckDuckGo extension, but only because it has "Unknown Privacy Practices." Zero trackers.

To clarify, it's on the user end, so anyone running adblockers or other privacy add-ons could control this, but that's a burden on visitors which I object to on principle.  If I disabled embedding this would be the "cleanest" website on the modern internet - mostly because it's so dated but also because I refuse to run ads.