people have a fundamental misunderstanding of what dark energy and dark matter are. they are unrelated and both are measurable effects. we don't know if the effect is there from physics being wrong, there being new types of matter or cosmological models being incorrect, and you have plenty of theories accounting for any variation of those, from gravity being wrong mond, to dark matter being a new type of particle like axions. anyone can measure the effect, but we still don't have evidence as to what exactly is wrong as all the theories we have also have fundamental flaws.
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