In some cases, unjust violence is claimed as self-defense by people. Hate crimes against minorities and marginalized people are often justified under the umbrella of self-defense. This why self-defense violence laws shouldn't exist, or it should be made sure that not all acts of violence are acts of self-defense.
There are sometimes power dynamics involved between the abuser and the victim. The abuser can shift the blame on the victim's act of self-defense by playing innocent.
People take advantage of self-defense laws by harming people and then blaming them for it, which is why violence isn't right even in the act of self-defense.