[chatGPT]> There is currently no evidence to suggest that dark energy can be compressed into a small volume and exhibit a gravitational pull in the same way that ordinary matter does. Dark energy is thought to be a property of the vacuum of space itself, and its effect on the universe is driven by its negative pressure, which causes the universe's expansion to accelerate.
Black hole masses are measured by observing their gravitational effects on surrounding matter and other astronomical objects. The mass of a black hole can be estimated by measuring the velocity of nearby stars or gas clouds and using the laws of gravity to infer the mass of the object producing the gravitational field. These measurements are based on our current understanding of gravity and are not affected by the presence or absence of dark energy.
However, it is worth noting that the properties of dark energy are still not fully understood, and there may be some new discoveries or developments in our understanding of gravity that could change our current understanding of these phenomena. Nonetheless, as of now, there is no evidence to suggest that dark energy can contribute to our measurements of black hole masses through its gravitational effects.
Is there some cosmological constraint that says dark energy compressed into a small volume would exhibit gravitational pull and therefore contribute to our measurements of black hole masses? If not then it feels like this is a weak counterargument that makes a pretty big assumption that dark energy must have the same mass-energy equivalence behaviour as regular energy from a general relativity perspective. If black holes somehow are the origin of dark energy, then surely this is driven by physics at energies far beyond our understanding from either particle physics or cosmology. In that case aren't basically all bets off in terms of what you'd expect to observe in terms of apparent black hole masses?