Hello,
Your site runs a HikaShop 6.6.0 package from August 29th. That package had an issue with the "Enable funding" and "Disable funding" settings of the PayPal Checkout payment method when they had never been saved: the labels of the payment means were sent to PayPal instead of their codes, PayPal refused to send its script, and the page displayed that message about the browser blocking PayPal, even though nothing in the browser was blocking it.
This was fixed in the 6.6.0 package on September 2nd. Download the 6.6.0 package again from your account and install it over your current version, and the buttons should appear again. If you can't update right away, edit the PayPal Checkout payment method, check the "Enable funding" and "Disable funding" settings, keeping only the payment means you want there, and save it.