If you use third party mining tools that charge a percent fee, the fee goes to an address owned by that tool provider.
It has nothing to do with the Zdash code.
Z-NOMP + official wallet
Why in a blockexplorer there is no information on the commission?
Zdash code requires some modifications to display more info.
I decided to hold back on making these modifications till some more people are on the team.
A couple of people I normally work with are extremely busy, so we will do this as soon as
all of us are on the same page. We are doing some work with the code locally for now and will
push to github when the time is right. Our focus for now is keeping Zdash growth, and get some
more exchanges through marketing. The community needs to participate in that as well as most
exchanges require community involvement. Please do not shy away from asking your favorite
exchange to add Zdash.