Dark energy is an expansion of spacetime itself that is uniformly present throughout the entire universe. If it were responsible for ʻOumuamua's acceleration it

Dark energy is an expansion of spacetime itself that is uniformly present throughout the entire universe. If it were responsible for ʻOumuamua's acceleration it would have been followed by our entire solar system being shredded down to subatomic particles shortly afterwards - see https://en.wikipedia.org/wiki/Big_Rip https://en.wikipedia.org/wiki/Big_Rip