How? If you didn't give it an internet connection, how is it sending any tracking data back to the mothership? It can't guess your wifi password or anything.
For starters, where do you think your router was manufactured? Can you trust it to only allow connections with your WiFi credentials?
Beyond that, there’s a broad range of products and manufacturers in an average house. Assuming none have struck a deal to do a credential-less connection with the router itself, they may be talking to each other, basically asking “do you know the WiFi?” To every device in your home. Then, they share the info with each other even though you haven’t granted it.
One of the comments in my past discussion on this topic noted that he didn’t even have his Wi-Fi setup, had just moved in to a new apartment, yet apparently his TV was knowledgeable about something similar. I don’t remember how he knew/found out but he suggested that it discovered his neighbors TV which was the same manufacturer and his neighbor did have it connected to their WiFi so the commentor’s TV leveraged the neighbors WiFi without being provided the credentials by a human.
My xiaomi TV is making thousands of request per day to their domains. I block them all using adguard/adblock, but imagine the amount of information they can get from a connected TV.
Samsung and LG and many others do this. Look for Automatic Content Recognition (ACR) in Samsung's privacy
This interesting study from last year: A First Look at Automatic Content Recognition Tracking in Smart TVs - https://arxiv.org/abs/2409.06203
Really, the only answer is privacy regulation. Any other solution (just let the free market handle it, don’t give it internet access, etc) is not workable in the long term.