My favorite part is that it cites a study at the bottom. There is no study about dual mask/triple mask effectiveness, it's an article in a paper that's the opinion of two people: https://indianexpress.com/article/explained/in-protecting-the-wearer-two-masks-can-be-better-than-one-scientists-say7151868/

There is an actual study out there that investigates multi-material discrete layers but that's different than two/three cloth masks as this is purporting: https://pubs.acs.org/doi/10.1021/acsnano.0c03252

Also note this study came out almost a year ago. I would also point out that during normal breathing you don't actually have a large aerosol spray, which this is supposed be effective at blocking. In fact, heavy breathing leads to more moisture buildup and would have a more concentrated aerosol and a higher exhale velocity (think if you've ever worn a cloth mask while skiing, at the end of a few runs it's fairly damp.)

Anyway, the whole study is interesting, but uses an ideal setup to determine the level of theoretical max blockage, and wouldn't be indicative of real world use/results.