Whisk barbeque sauce, vinegar, brown sugar, garlic powder, and red pepper flakes together in a bowl until the sugar dissolves; pour over the chicken.
1 (18 ounce) bottle barbeque sauce (such as Sweet Baby Ray's®), ¼ cup distilled white vinegar, ¼ cup brown sugar, ½ teaspoon red pepper flakes, teaspoon garlic powder
