Meiosis II is not called a reduction division because the resulting cells still hold:

1. A reduction division is one that halves the number of chromosome sets. 2. Meiosis I does that, taking the cell from two sets to one. 3. Meiosis II is not a reduction division because although there are fewer copies of the genome in the resulting cells, there is still one set of chromosomes, as there was at the end of meiosis I. 4. What meiosis II separates is sister chromatids, which does not change the number of sets. 5. So the ploidy is unchanged across the second division. _Source: OpenStax Biology for AP(R) Courses (CC BY 4.0), Ch 11 'Meiosis and Sexual Reproduction', sections 11.1-11.2_