I have read about lots of alternatives to dark matter theory in the past, many BS, but this one seems to be a perfectly credible one;
https://phys.org/news/2020-12-unique-gravity-dark-theory.html
"...Instead of attributing the excess gravitational pull to an unseen, undetectable dark matter, MOND suggests that gravity at low accelerations is stronger than would be predicted by a pure Newtonian understanding.
In addition, MOND made a bold prediction: the internal motions of an object in the cosmos should not only depend on the mass of the object itself, but also the gravitational pull from all other masses in the universe—called "the external field effect" (EFE).
Milgrom said the findings, if robustly confirmed, would be "the smoking gun proving that galaxies are governed by modified dynamics rather than obeying the laws of Newton and of general relativity."
150 galaxies tested for EFE
McGaugh and his collaborators, led by Kyu-Hyun Chae, from Sejong University in South Korea, say they detected this EFE in more than 150 galaxies studied.
...
"The external field effect is a unique signature of MOND that does not occur in Newton-Einstein gravity," McGaugh said. "This has no analogy in conventional theory with dark matter. Detection of this effect is a real head-scratcher."
...
The scientists said they deduced the EFE by observing that galaxies in strong external fields slowed (or exhibited declining rotation curves) more frequently than galaxies in weaker external fields—as predicted by MOND alone.
..."
There already seems to be good evidence supporting this one, which makes it currently look very promising. But I guess we will still just have to wait and see if this alternative to dark matter theory endures the test of time of observations and evidence and continuous scientific scrutiny.