Isn't this the best place to deliver that message?
Also, the idea that she'll get taxed more for being in a higher income scale is a logical outcome of the policy she proposes. If she wants to have her own income partially redistibuted, then it's totally okay to advocate for that position.
I found the dress a bit cringy, but activism ussually is. But I don't really see the "hypocrisy" people are talking about. Most of the criticism comes from people that have this idea that when she says: "tax the rich" she doesn't mean herself, but I don't see a reason for that idea to be true.