that is because you are using blockchain.info to check how much fee you paid and that site has not implemented anything of SegWit yet. what happens is that satoshi/byte is also deprecated because of introduction of "weight". so you should report your fees in satsohi per virtual bytes.
what you paid was probably 1 s/vb but since blockchain.info doesn't know what SegWit is they show you the s/b value which is lower because size in byte is bigger for a SegWit transaction.

check out https://btc.com/ explorer for real values.