Why does my smart TV seem to be using so much data despite not streaming any content?

I totally understand your concern, especially with a limited data plan. I've had similar issues with my smart TV in the past, and I think I can help you troubleshoot this.

Firstly, it's worth checking if your TV is set to check for software updates automatically. Sometimes these updates can continue to run in the background even after you've turned off auto-update. To check this, go to your TV's settings, then select 'System', and look for 'Software Update'. Make sure it's set to 'Manual' or 'Off'. Also, check if your TV is set to automatically download and install new features or apps. You can usually find this setting in the same 'System' menu.

Another possibility is that your TV is still connected to the internet even when you think it's not. Check if your Wi-Fi is turned off or set to 'Limited Access' when you're not using your TV. You can do this by going to your TV's settings, then selecting 'Network', and looking for your Wi-Fi network. If it's still connected, try disconnecting it and see if your data usage drops. It's also a good idea to check your router's settings to see if there are any devices connected to it that you're not aware of.

Lastly, if none of these suggestions work, it's possible that there's a software issue with your TV or a problem with your internet connection. In this case, you might want to contact your TV's manufacturer or your internet service provider for further assistance. They may be able to help you troubleshoot the issue or provide more specific advice on how to reduce your data usage.