WD Blue 1TB HDD capacity shrinking?

I just installed a Western Digital 1TB hard drive in my PS4 a couple of days ago. After reinstalling the PS4’s firmware/OS, the max capacity of the hard drive was 862GB. Then yesterday it was 861GB, and today it’s 860GB. Any reason why it’s shrinking? Is this bad?

In case anyone wants to know, this is the hard drive I purchased:



I haven’s seen something like this.

Have you tried contacting Sony support to see if they have any information about this?