Read further down in the study. It discusses exactly what i'm referring to in that air was pushed out the sides with KN95 masks and one of the reasons cloth masks performed better then KN95s was a better fit.
And it showed that KN95s are NOT perfect at blocking COVID. This is why the general public now distrust scientists, because the media presents it to them inaccurately and tells them results the study never found. Science is about precision. The study did not find all N95s where nearly perfect at blocking covid, that's flat out inaccurate.
Also let's be really precise here. I'm not conflating anything and i think you don't realize you are.
1) KN95 and N95 use similar filter materials they both have to filter 95% of particles down to 3 microns, the difference is to do with certification N95 is a US certification and KN95 is a Chinese certification. So the material is essentially the same between them. The fits tend to be different.
2) What i'm getting at is the title said all N95s, that's not what the study found, it found that a specific fit style "duckbill" was "Nearly Perfect at Blocking COVID" the non duckbills did not.
So to be accurate what the study did NOT find which the title suggests is that all US certified masks that filter 95% of particles down to 3 microns were nearly perfect at blocking COVID.
Generally speaking, N95s fit better than KN95s, because earloops aren't allowed in the N95 standard, and headbands provide more tension so there's a better face seal. This study only evaluated one brand of N95, but there are many other people that have tested various respirators with generally the same conclusions.