I am using this LG TV 43UJ752T since May 2018 and I was able to play 4K HDR videos on youtube without any issues. I used to get 40 to 68 Mbps speed if I enable the "stats for nerds" option on youtube app.
But after this webOS 6.0 update.. I am able to see only 12 to 22 Mbps speed and the 4K videos on youtube started buffering a lot. The buffer health is now 2 seconds .. but before it was 8 to 15 seconds.
in my laptop and other devices I am getting 120Mbps speed. There is no problem with my wifi router and I have tried to connect the TV with 5GHz band.. But the wifi speed issue remains same on TV.
Caution: Please dont enable automatic updates on your webOS TV.