There is nothing to fix here, that the discount, that the margin, are applied to the purchase price. This needs to be improved.
You have a markup of 14% on the price, and a discount of 30%, but the purchase price does not change from this.
As far as I understand, you need to make a discount on the purchase price and write this price on the card as the purchase price.
Your options are:
1) If all the supplier's goods have RRP, then disable the discount, it does not appear anywhere at all according to the examples that you sent.
2) Set up markup through automation for products - actions when saving a product card. Calculate prices using formulas. but such formulas will need to be done in order to set up for all suppliers.
3) Modify so that the discount can be put down on the purchase price - that is, we set 30% and this discount is applied not to the sale price but to the purchase price, and already at this price of the supplier, taking into account the discount, there was an extra charge, and the sale price was considered.
4) Load the discount into the position.
That is, in order for it to work as I wrote, you need the discount to be registered here
https://i.imgur.com/vFPj0b7.pngIn your case, specifically for this supplier, you need to specify a discount in the price
https://i.imgur.com/0vfCHM6.pngIf this is xml, then you can do this
https://i.imgur.com/n2M4Eoi.png