IFRS15-financing comment

sir in IFRS 15 when there is financing component involved, then we take PV of future consideration receivable discounted t customer’s borrowing rate.

So here my doubt is that why do we take customer’s borrowing rate? Shouldn’t it be seller’s borrowing borrowing rate? Theoretically, if the customer is being given significant time to pay back, then that means supplier is borrowing meanwhile(though bank ODetc.)