Well, first, I don't regularly use the term "toxic femininity" because I don't feel it accurately describes the dynamic to which I'm referring.
Secondly, "prejudice" implies a passive thought or belief. Once someone makes their so-called prejudice ACTIONABLE or BEHAVIORAL, it moves beyond "prejudice" and enters the realm of bigotry and discrimination.
So, while some people's prejudices can be misandrist in nature -- that doesn't automatically mean all misandry is "merely prejudice" by default.
When you reference power dynamics: I suspect you're referring to the fact that misogyny is so often systemic in addition to being social and cultural? By contrast, misandry is more prevalently social and cultural...but not routinely systemic in the way that misogyny tends to be.
So are you centering how the patriarchy manifests, as a system? Yes, in that context, misandry wouldn't be as prevalent of a factor. That still doesn't mean it isn't wrong, when/if it happens. That still doesn't mean we (as a society) should enable it, *if* we observe or encounter it. Multiple things can be true (or in play) at the same time.
Finally, I'm not saying you are necessarily gaslighting someone else JUST BECAUSE you disagree with them. But, yes, minimizing and marginalizing another person's experiences due to their identity *IS* indeed a form of gaslighting. And I'll admit I've been guilty of it, in the past -- and try not to be, in the present.