Do mathematicians have any opinion on the mathermatical "fixes" attempting to reconcile "Dark Matter" with Einstein's theory of Relativity?

The concept of "Dark Matter" has been causing considerable inconvenience for physicists for some decades now. https://www.youtube.com/watch?v=aUtdLfdnpzs In response, physicists have developed a number of mathematical "fixes" attempting to reconcile "Dark Matter", and some other inconveniences, with Einstein's Theory of Relativity https://en.wikipedia.org/wiki/Modified_Newtonian_dynamics https://en.wikipedia.org/wiki/Alternatives_to_general_relativity I was wondering if mathematicians have any views on these particular questions? To me, in simple intuitive terms, Einstein's Theory of Relativity is based on the notion that Light defines the Universe as a whole, so, given we now know that 90% of the matter in the universe doesn't interact with light, at all, ever, then, essentially, the Theory of Relativity is wrong. Any thoughts?