It uses the YouTube API, which still shows dislike data. They will switch to inferior methods once the data in December when dislikes are removed from the API. I would indeed prefer it to show "unknown" rather than just guessing, although there is also value in displaying the views:likes ratio separately.

Someone will likely build a browser extension that tracks dislikes outside of YouTube and those who want some metric will install it and vote on videos. Just my guess.

Considering literally everyone wants them back, it would be funny if a browser like Firefox or Brave would just build it in as a feature.