[Night_Thastus]

Is there a way to set up the modem, router, pihole, or any other part of the network to close that loophole?

[inetknght]

Yes. Put your TV behind a second router, manually assign IP address and route to your local network, and don't give the router an upstream gateway. Then any packets the TV might send even to a plain IP address will be dropped at its router before reaching your main router.

[wpm]

One can also just run an open source router/firewall software and do this by clicking a few buttons. OPNsense or OpenWRT get the job done wonderfully.