And then 2019 was also so bad that they just stopped doing it entirely.
On a different note, there's a browser extension that lets you see dislikes. The video with the most dislikes relative to likes is the one where the late Susan Wojcicki accepts a Free Expression Award. As of this writing, it has over 75k dislikes and less than 300 likes.
On yet another different note, not to get political, but another reason they got rid of them was because they got caught reducing the number of dislikes on Joe Biden's White House videos because they were getting severely negative reception.