troubleshooting – Is the noise coming from fast aperture ring adjustments of Sigma 100-400m lens on Sony A6500 expected?

I recently got a Sigma 100-400mm for my Sony A6500 and love it so far. But I noticed that the aperture ring makes noticeable noise on power ON and power OFF. See Google Photos album of two videos showing this.

Is the noise expected? And how do I prevent mechanical wear, is it possible to switch off this action for power ON/OFF?