I tend to agree that the postulated dark matter can't be behaving the same as regular matter or we would not even be able to tell that there is something different going on compared to the gravity we expect from the matter we can see. If there was a constant ratio of dark matter to regular matter, then we would just think that regular matter weighs the same as the actual combination.
So, your definition of the observation of apparent gravitational attraction from something we do not detect is fundamentally correct.
There is still argument over whether that is due to incorrect expectations for gravity from matter we can detect (i.e., alternate formulations of the physical law of gravity) or some sort of matter that we cannot detect. Having spent a lot of time looking and theorizing about what other form of matter could exist that we are not detecting - and coming up empty, so far - there is a lot of effort on reevaluating the law of gravity. And, that is as it should be. But, we do not seem to be making much progress on either, so far.
Unless the Rubin Telescope gives us a new insight that allows us to actually understand the underlying physics which we obviously do not understand right now, all the new data can do is to provide more precise data on the observed phenomena so that theorists can more finely tune the fudge factors in their theories.