Unrated comments are now classified as neutral
Feedback submitted without a thumbs up or a thumbs down is now classified as neutral rather than negative.

The old behavior skewed sentiment on every project where people wrote a comment and skipped the rating, which is common on documentation pages. Counting those as negative assumed an intent the user never expressed.
There is nothing to configure. New submissions are classified this way automatically.
Your sentiment trend will step when this takes effect, so read the change date as a break in the series rather than a real shift in how readers feel.
Sentiment by page lives in the feedback management tool.