User blog comment:Kunoichi101/Chapter 958 Bad Omens in Wano/@comment-2001:8003:100A:5100:F9F9:4BB6:5ADA:A4FD-20191004122616/@comment-118.211.53.97-20191004125725

There were signs of a traitor going back as far as Zou after the Beast Pirates found their way to Zou twice. The minks were even wondering how Jack found his way there twice.

There are other things to consider the traitor was privy to some stuff that Hiyori shouldn't have known due to not being around to hear it.

Hiyori being a traitor is even less likely than Kyoshiro being Denjiro in my opinion.