Some TV manufacturers have gotten wise to this (sigh) and started hard-coding their DNS lookup IPs.
Is there a list of such manufactures? Don't want to accidentally buy one of their products.
Of course google and other spy companies are pushing DNS over HTTPS, so once that becomes popular in these devices, you're screwed - you simply have to block all traffic (in which case you won't be able to watch netflix/disney/whatever using that device. For a TV that's fine, as you have a PC plugged into it, for now)