At present for most of the content on the platform the number of "thumbs down" votes is displayed alongside the number of "thumbs up" votes that a given video receives.
Having experimented with it for a while now the company has decided to proceed. So you'll notice a growing percentage of content available that only shows the number of "thumbs up" it gets. Content creators will still be able to see the number of "thumbs down" votes on the back end but those numbers will no longer be available for public consumption.
According to various statements the company has made along the way the goal here is to cut off a potential vector for harassment. Based on the comments found in many videos a significant percentage of users left message saying something to the effect of "I just came here to leave a dislike."
While there's merit in the company's thinking it hides a slightly more selfish purpose as well. In all of YouTube history the single most disliked video is the company's own "Rewind from 2018" video. In fact that video earned so much negative press that the company has since opted to cancel their Rewind videos altogether.
YouTube is certainly not the first company to make the decision to hide negative rating metrics. Twitter for example allows users to hide the number of likes a tweet gets at the poster's option.
No matter what your opinion is it is important to stress that as a content creator you'll still have access to that information. The hope is simply that it won't be used by viewers to create a negative feedback loop.