Need help understanding discounts before or after taxes

I cannot understand how discounts are applied in “Before Taxes” or “After Taxes” mode.

We have a single tax at 22% and I want a discount of, let’s say, 5€.

In “before taxes” mode I can set it at 4.10€ and, since it’s applied before taxes, the result will be -4.10*1.22, resulting in a 5€ discount.

I cannot understand why I still have to set it at 4.10€, even in “after taxes” mode, to obtain 5€.
It seems to me that the calculation is no different from the previous example.

What am I missing here?

Thank you very much.