I think I found the issue.
For your information, my Products have a 7 % VAT
100 => 107 %
93,457 => 100 %
79,439 = > 85 % (Provision for the Vendor)
100 – 79,439 = 20,561 Cent = 0,21 EUR (Admin Commission).

But in my opinion, this is not right. You calculate the provision for the Vendor with the net price. But the commission for the admin, you calculate the product price incl. VAT with the net provision from the vendor. You mix the VAT.

Is this right? Is this the right way?

Best regards