Multiple studies have shown that masks are effective at curbing the spread of COVID 19. The paper in the OP heavily cherry picks studies to conclude that masks don't work and does not provide any real explanation as to why someone would be better off in a room with someone shedding COVID 19 virus than they would with a mask. You really just have to believe in magic and ignore science to believe that a mask offers no protection. And all the stuff about masks being harmful is genuinely dishonest. The author picks some studies that generally look at oxygen deprivation and concludes that the same results will happen if you wear a mask.
https://jamanetwork.com/journals/jama/fullarticle/2776536