There’s a big debate now about whether dark matter really exists or there’s a better explanation for how most of the mass of the universe seems to be unable to be perceived. Related to gravitational waves lately I believe.
Take this for what it is I’m not a scientist I just occasionally read science articles.
I think you’re getting confused with dark energy. There is very little debate about dark matter–it’s an observation that many many many people have made.
Dark energy is the name for whatever is causing the explanation expansion rate of the universe to increase. There’s quite a bit of debate about whether the expansion rate even IS increasing. And the amount of increase is different according to how you try to observe it. So yeah, there’s a lot of debate about whether dark energy is actually a thing, but there is very little debate on whether there’s more matter than we’re able to observe, something that we call dark matter but which we don’t really understand. Similar names, but totally different concepts!
I thought the only observation we have of dark matter is via cosmological models.
It’s long been stated by astronomers it’s an ad hoc theory until they figure out what’s going on.