It is at variance with General Relativity. I do NOT know if it can be incorporated into an invariant theory like GR.

I have always doubted "Dark Matter" because it seemed too much like "ghost matter". Since it was "detected" ONLY by its gravitation effects, I suspected that it was due to defects in the theory of gravity.

If I had to place a bet on "Dark Matter" really existing or not, I would vote "NO".