I want to find in code place, where PayPal query sends, with Payflowpro Credit/Debit card payment method on checkout. Please, help me with it.
If you need a place where exactly PayPal Payflow sends request from Magento to PayPal gateway then you need \Magento\Paypal\Model\Payflow\Service\Gateway::postRequest method. This method uses curl to perform all operations, like authorize, capture, void, etc.
But if you need the place, where Magento sends request from payment card form to PayPal, you need to look through app/code/Magento/Paypal/view/frontend/web/js/view/payment/method-renderer/payflowpro-method.js.