Amazon sent me an email stating that as of September 26, 2019, they would no longer support the built in Amazon Prime video application on my Panasonic Smart TV. To make up for this loss of functionality they included a $25 discount code for a Fire TV stick.
FWIW, I'm an Amazon Prime member who watches no more than one Amazon video on this TV per month. The coupon code sent appears to be a single use code.
BOLO for same of you are in a similar situation.