Summary - PayPal web page isn't checking that the MacBook is closed when accessing the touch ID.
I access PayPal on my MacBook pro, with the touch ID sensor using Safari to the PayPal web page.
Starting recently, when I navigate to the Paypal web page, I see a dialog that tells me that I have touch ID enabled. Th web page pauses for a few seconds, then proceeds to tell me I'm logged in. It's clear the Paypal web page isn't actually checking the Touch ID, as the lid is closed, and the sensor isn't accessible.