[magnostherobot]

Interestingly I would use the use of "the patriarchy" as a term as evidence against the belief of the transformation of the meaning of the phrase "toxic masculinity". The patriarchy doesn't have a qualifier: that a patriarchy exists is considered bad innately, and so the term doesn't need its own "toxic" prepended. Masculinity, on the other hand, is not considered innately bad, and so requires the "toxic" qualifier to narrow the target to the portions of masculinity which are... well, toxic. If the "toxic" was superfluous (due to masculinity being seen as inherently evil, for example), surely people would have dropped it ages ago.

This is, of course, based on my personal experience with these phrases. When my friends and I use "toxic masculinity", we can see the difference between it and "masculinity", and when I see the phrase used by strangers online, I assume that they're using it as "the part of masculinity that is toxic". I can't remember any situation where that assumption has misled me, although maybe I wouldn't remember something like that.

You're certainly right about some people using the "toxic" as an adjective, insofar as I believe this author has done exactly that in this article. If I was feeling cynical, I might argue that the author may have deliberately conflated all of masculinity with its elements that get called "toxic", in an attempt to make the two seem inseparable. I think the good faith interpretation is simply that this is how the author has seen the phrase used before, and that, somewhere between my circles and his circles, the phrase's meaning has been changed or accidentally misinterpreted.