When retrieving a list of works in the API, the authorships list within each work will be cut off at 100 authorships objects in order to keep things running well. When this happens the boolean value is_authors_truncated will be available and set to true. This affects a small portion of OpenAlex, as there are around 35,000 works with more than 100 authors. This limitation does not apply to the data snapshot.
This affects filtering as well. So if you filter works using an author ID or ROR, you will not receive works where that author is listed further than 100 places down on the list of authors. We plan to change this in the future, so that filtering works as expected.