Loose parts inside the AirPods Pro 2

I’ve noticed an issue with my left AirPod. When I shake it, I can feel something loose or moving inside. The playback and sound are fine, but it concerns me because it doesn’t happen with the right AirPod. The noise stops when I leave it stationary in the case for a while, but it starts again if I shake it hard. I haven’t dropped it recently or exposed it to water. 

NB: it’s still under warranty