Why are all posts from the group not retrieved via group.getStatTopics?

Question

Classmates

I used their standard function to retrieve posts from a group: group.getStatTopics.
It gives me the necessary results, but they are not complete. For example, only a small part of the entire set of posts is displayed. The count parameter does not return the full array, some posts are missing. Also, the totalCount parameter is not emitted.