According to the United States Department of Agriculture (USDA) guidelines, perishable foods like meat should not be left at temperatures between 40°F (4°C) and 140°F (60°C) for more than two hours.
When food is left in the "danger zone" (between 40°F and 140°F), bacteria can multiply rapidly, increasing the risk of foodborne illness. Freezing helps to slow down bacterial growth, but it does not kill bacteria. So if frozen chicken is left out for an extended period, harmful bacteria may have multiplied to dangerous levels.
To ensure food safety, it's best to discard chicken that has been left out at room temperature for more than two hours. It's not worth the risk of consuming potentially contaminated food, as it could lead to food poisoning. If you have any doubts about the safety of the chicken, it's always better to err on the side of caution and throw it away.