Previously, previously, previously, previously, previously, previously, previously.
So yet again we get people saying that 'dark energy', the only free parameter in General Relativity which, because people misinterpreted a remark by Einstein, we somehow all assumed was zero for 80 years without any evidence at all that it was, is this big mysterious thing. And we do that because the standard model, which has free parameters pouring out of every orifice (I thought it was 17, but no, it's 19, at least this week) somehow fails to predict it. This is like saying that flat-earthers find the precession of the perihelion of Mercury a big mysterious thing.
(Not entirely serious, but, really, so GR has one parameter and it turns out not to be zero, get over it.)
When do you suppose the dark matter theorists will stop using monochromatic mass distributions to characterize merging bodies like black holes. There are many possibilities for widely platykurtic distributions that fit all the bills, but we still look for particles.
No-one thinks black holes are made of particles in any useful sense: they're made of geometry. Dark matter theorists don't look for black hole collisions to my knowledge (the whole primordial BH model of dark matter is pretty much known to be false at this point by microlensing surveys).
... Microlensing surveys which assume a monochromatic mass distribution of black holes! Remove that assumption and the constraints melt away.