Why mismatch between number of data points and number of vectors created?

In the lesson-3 Recommender Systems, in the default practise notebook we use a dataset of 100 observations from.csv file (nrows=100) for creating embedding vectors of df['article'] and storing in PineconeVDB. Why is that we see that number of vectors created as 1000. as shown in:

{'dimension': 1536,
 'index_fullness': 0.0,
 'namespaces': {'': {'vector_count': 1000}},
 'total_vector_count': 1000}

Similarly in the demo by the instructor, he selected 1000 rows from the CSV, but he got 10500 vectors created. I think the reason is to do with the chunking of the data by text_splitter. Can someone explain the calculation behind this? Thank you.