As you can see from the filtration data, Well Before masks offer good production, so why did it fail the KN95 standard?
Because an important part of the KN95 standard requires that the mask have breathability that falls below 250 pa, and have both the manufacturer name and the standard to which the mask is adhering, in this case GB 2626-2019, written across the front of the mask.
The newer versions are now completely up to standard, which is why we are now comfortable marking this as a mask you should buy.