Q: Speed discrepancy appears in all iPhone 7 32GB models

Hi! I saw a video about iPhone 7 storage writing speed. Is it real that the 32 GB version of the iPhone 7 storage writing speed is slower than the 256 GB version of it? I have a 32 GB version iPhone 7 but if it is real I won't buy iPhone anymore. It makes me very angry? Here is the link for the video https://www.youtube.com/watch?v=qW2-TIbcTIg&feature=youtu.be