Though often they get it wrong, like when I bought a movie off Apple and it errored when I screen mirrored to my dumb TV and it’s back to piracy first for me.
Your dumb TV doesn't have the appropriate HDCP chips, which is why it errored. Your computer didn't know whether it was a dumb TV or if it was an HDMI capture card ready to rip the movie...
Not that I agree with the practice.