FLE2 compaction for range fields calculate the number of padding documents to be inserted, and creates that may ESC padding documents. The resulting vector of documents is then passed to FLEQueryInterface::insertDocuments() all at once, which then creates a batch insert command containing all of the input documents.  If the number of padding documents is very large, this might either cause the resulting command BSONObject to exceed the 16MB limit, or exceed the 100,000 document limit for batched inserts.