The answer to 'why is my recessed lighting buzzing noise' is that a buzzing or humming sound from recessed lights is often caused by a faulty transformer or driver. This can happen when the transformer or driver is going bad, or if it's not properly matched to the LED bulbs you're using.
Other common causes include loose connections, improper wiring, or issues with the electrical circuit supplying power to the lights. In some cases, the buzzing may be caused by interference from other electrical devices nearby. It's important to diagnose and address the root cause to eliminate the buzzing noise.