I've kind of noticed this, too. I actually use a LG OLED as my primary desktop PC monitor in my master bedroom, mounted to the wall above a standing desk. I don't usually use it as an actual television for basic sleep hygiene reasons, but I've used it more than zero times in the two years I've had it now, and never noticed any ads in any interface (excluding the streaming apps themselves promotion their own content in their apps).

Same thing on the Sony Bravia I have in my living room, which is what I usually watch television on.

But I do run my own DNS server in an OPNSense router/firewall with some pretty strict blocking rules, and it recurses to a NextDNS server that also has its own blocklists enabled. So if these devices are actually using DNS via DHCP instead of hard-coding their own servers, and serving ads from known ad domains, that would do it.

Checking your profile you're not in the US. I also asked some friends in RO an DE and they say no ads either.

Not sure if LG hasn't got around to sourcing ads for the EU or they're not doing it because of some legal reasons.

Edit: got some screenshots. Apparently you need to agree to the terms and conditions to get ads on a RO LG. Don't know who ever does that.

Serbia is not in EU, but you probably are right.