In my experience, actual KN95s have extensive leakage, especially around the nose. One factor may be that Western faces and Asian faces are different, and my understanding is that the KN95 standard and masks are tailored to Asian facial structures.
For instance, this is an assessment of a KN95 style mask I actually bought at a Menard's clearance a few months ago. It definitely has fit problems around my nose.
https://www.cdc.gov/niosh/npptl/respirators/testing/results/...
> While the above-listed product classification has similar performance requirements to NIOSH-approved devices, NIOSH does not have knowledge about the sustained manufacturer quality system and product quality control for these products. NIOSH also does not have knowledge about the product’s handling and exposures after leaving its manufacturer’s control.
> In addition, this product is an ear loop design. Currently, there are no NIOSH-approved products with ear loops; NIOSH-approved N95s have head bands. Furthermore,limited assessment of ear loop designs, indicate difficulty achieving a proper fit. While filter efficiency shows how well the filter media performs, users mustensure a proper fit is achieved.