Not activated nor linked to any social media.
By chance, is your TV a late model? Something that has access to the “internet of things?”
Anyway, my guesses are 1) merry pranksters; 2) someone testing a genuine message that is going out the wrong way (testing on a signal/channel someone thinks is not in use); 3) a genuine message being sent out and somehow your TV is sensitive to its reception. (Like a closed-circuit signal that is somehow being broadcast that your TV is able to pick up.)
I’m not a broadcast nor electronics engineer, so sorry to those who are for mangling or conflating terms or concepts.