For domesticated food that’s not much of a problem. Wild food, it can be. Especially predators, since they get toxin when they eat liver, and those toxins wind up in their liver. You can get some pretty supercharged unpleasantness. Of course then there’s just the fact that it has a weird texture and doesn’t taste that great.
I think people historically ate organ meats out of necessity in times of severe want.
It’s worse than that. Any liver, including from domesticated animals, contains potentially toxic amounts of vitamin A. Lethal in extreme cases. So ... some people reccomend eating no more than 3oz of beef liver per week, or no more than 3 oz of chicken liver twice per week.