I also went into adding an order and added the same product as you, my price was correct
https://prnt.sc/yvd1gqThe only moment why this can happen for you is when you add an order to the supplier, and since the order to the supplier has an "outgoing" direction of the process, the purchase price is also set.
To find out which process you are adding, you need to click the "Advanced settings" button and look in the "Business process" field what is selected, like this
https://prnt.sc/yvdbh5When you find out which business process you are adding, you can go to the system settings - business processes, in the list of business processes, select the one that you specify when creating, go to the business process (by clicking on the name) and select "Parameters" https in the drop-down list ://prnt.sc/yvdkkl in the menu that opens, you can see which direction the process has
https://prnt.sc/yvdnxp