It is unlikely that you would break a bracket by brushing your teeth with proper technique. Brackets are designed to be durable and withstand the normal forces exerted during daily activities, including brushing.
However, using a hard-bristled toothbrush or brushing with excessive force could potentially damage the bracket or cause other issues. To avoid any risk, use a soft-bristled toothbrush and gentle brushing motions.
If you notice any issues with your brackets or feel that they might be loose or damaged, consult your orthodontist for an evaluation.