A serial number can be any format the manufacturer likes, personally I think a format like that would be great, as it makes a lot of sense down the line…… If you’re genuinely not sure, just call Kona, it’s a current bike so there shouldn’t be any ambiguity and they can prob register the warranty for you at the same time negating any doubt…….
Everything there looks legit to me. 2104 is the month and year which would tally with 22 sale. from what I recall, but happy to be wrong.
If it is a fake, it's a damn good one and it looks well built with decent welds and materials used.
ride it, stop worrying about and just enjoy.