We’ve seen stars disappear before (presumably forming black holes), but this is by far the clearest and most detailed observed example. It strongly confirms the theory of “failed supernovae,” where sufficiently massive stars collapse directly into black holes without a bright explosion. This implies the universe likely contains far more stellar-mass black holes than previously estimated.

As an amateur, I briefly thought that this could help us address the issue of dark matter but from what I gather - no. Even with this increase of black holes the new matter would not be even close to addressing the dark matter gap (like orders of magnitude off still)

TL;DR: confirms that the universe has more stellar-mass black holes than thought but nothing major of it.