We know pretty well what matter is and how it interacts with the others.
Dark matter interacts through gravity but not light. Beyond that I haven’t heard much else.
And lastly anti-matter has an opposite charge and interacts with matter through annihilation. I think I remember hearing that it would react with dark matter the same way.
So my question is, does anti-dark matter exist, and what are it’s properties?
There are hypothesis that dark matter particles are their own anti particle, which would mean that they would annihilate when they come in contact with each other.
The people looking for them are examining high energy bursts around supermassive black holes as potentially coming from that. No idea how they could ever approach finding any evidence for that. But that’s their problem.