What to do when your AirPods start leaking sound, when others can hear sound from your AirPods even at a low volume?

Again only the AirPods Pro come with multiple sized eartips. The AirPods do not and are "one-size-fit-all" types of devices. It may be possible that the AirPods that you received are faulty. I suggest that you pay a visit to your local Apple Store or Apple Authorized Service Provider to have them take a look and provide you with your options. Alternatively, if it is still within 14 days of purchase, you can return them for either a refund or replacement.

My guess is that these particular AirPods do not fit your ear "perfectly" and sound is "leaking" do to an improper fit. Are these AirPods or AirPod Pros? With the latter, you should have been provided with three different sized ear tips to try.