Prorate for subscription plan

[xiao91]

Based on the document that Shopify provides, they are doing the calculation for us when there is a plan changes.

I had a Basic plan 100 and approved the changes(Screenshot 1). Then i did a another one upgrade cost 150, the difference between these two plan is 50 dollar. So i am expecting a prorate with the difference showing in the screenshot 2 of 50 of some sort. But the payment confirmation payment is showing the full amount of 150.

screenshot 1

screenshot 2