Paypal checkout transfers the amount to be debited from the client?

Question

API

Good afternoon! Prompt, please, who faced.
Added paypal checkout script to the site . Everything works, but the amount to be deducted is specified in the script on the client! The server receives a notification that the payment has passed and the payment ID.
Tell me is it okay? I have never seen this before, everywhere the amount for payment was formed on the server.