So, if so-called "toxic masculinity" is responsible for sexual assaults, is "toxic femininity" responsible for false accusations of sexual assault?
I don't think we should say that toxic masculinity is responsible. It (or a set of attitudes that together are sometimes called toxic masculinity, or something similar) is (or are) just risk factors, apparently, along with other factors, such as for example alcohol (in relation to sexual assaults specifically in that case).
Most likely, almost inevitably (because they have to do with human behaviour and thinking) such things will have both biological and learned/cultural/social components.
In my humble opinion, toxic masculinity as an idea and a term shares something with for example the idea of patriarchy, in the sense that maybe, at times, it's overstated, or used as a catch-all explanation in sometimes vague terms, perhaps including by feminists. But almost anything can be exaggerated or overused as an explanation about almost anything. That doesn't mean it's not a valid or useful explanation (which imo both those ideas/terms are) just that it or they are not
as much of an explanation or not an explanation as often as some (emphasis
some only) might feel.
I think it's fair to say (I stand to be corrected) that toxic masculinity has come to be associated with being brought into discussions either by feminists or those influenced by or alluding to feminist ideas (even though I believe the term was coined by a male, non-feminist sociologist). As such, I wonder if the term has become a bit of a trigger for some who don't like feminism much and thus something to more or less automatically recoil from, or counter, perhaps unnecessarily.
In other words, despite all its flaws, I think it's quite a good term to describe...what it is the OP is describing.