When requesting availability data from WeatherKit Rest API I am currently seeing an addition undocumented dataset name: trendComparison. https://developer.apple.com/documentation/weatherkitrestapi/dataset
What is this dataset? Is it new data or is it a mistake? Will the documentation be updated?
See a similar finding in this thread: WeatherKit REST API new columns for CurrentWeather.
Basically, if it’s not documented, it doesn’t exist. Just make sure your parsing logic safely ignores any objects or fields it doesn’t recognize.