They literally run speech to text, store it and exfiltrate it to their servers…

Even if you deny internet access, it can hop to other smart devices of the same brand using hidden SSIDs and exfiltratr data that way, or if the TV gets sold and connected to a network, all of the stored conversations will get sent to their servers. This was from the original GN investigation and associated security researchers

There isn’t really something one can network-admin a way out of it seems, sadly…