Hey Jason,
I'm curious if you can provide an example curl (with limit and offset) that resulted in data being returned from a year ago--hopefully if there is a bug that data can help us correct it. Just scanning the return results with limit=100, I'm not seeing any examples of data from a year ago.
With respect to what is considered a "New Release", our backend teams have a daily job that queries content by popularity and release date and serves that data as a result of this endpoint call. Unfortunately there's currently not a way to provide a date-range for this endpoint to narrow the results, so any filtering for specific time ranges would have to be on the client side (your implementation).
Hopefully this was helpful, but please let me know if you have any additional questions, comments, or concerns.
Best,
Dillon Easter