The Quillette article Studying the Link Between Race and Police Killings is a good summary of why results can appear contradictory or inconclusive in different studies. Advocates, of course, pick the studies that show what they like and trumpet those. The rest of us have to have higher standards than that.
Consider, as a thought experiment, data showing that a white police officer was less likely to shoot a black person once the officer had unholstered his or her gun. On the surface, this would look like evidence against racist intent. But this inference becomes much weaker—and perhaps even unsustainable—if one considers the possibility that officers are significantly more likely to unholster and aim their weapons at blacks to begin with. This field is full of puzzles such as this.