Yeah, I see the same!
Actually they have a couple of 8K videos, that at first I thought would be 8K on the 950R, because there were no longer the little "4K" sign next to them as I have been used to on so many other 8K videos. But unfortunately not; the tv refuses to play any 8K YouTube videoes. I feel betrayed by Samsung, who keeps referring to Google/YouTube to fix it :-(
In these 2 shoys taken of my 800t you can see waht I mean by the codecs. The avo1 will play and shows 8k is playing but the upload I did from my Note 20 Ultra in 8k is in VP9 and will only play in 4k, even though it was uploaded as 8k. Not sure as how to change the codec. When it was first uploaded it would play in 1080p and had the AV01 codec, then it was processed by youtube and went up to 4k but with the VP9 codec.
Unfortunately our TVs do not have Av1 support. It will not work. Hopefully the will have a device like a firestick that will allow Av1 support. The 2020 Samsung models have Av1 support.
Just search '8k' on the YouTube app. There are a lot of videos that appear, some are actually 8k, others just say they are. They will all have the 4k badge on them. But after you click on the video, navigate to the three dots (More) it will open up a menu that says quality. If the 'quality' badge is 8k, then it is an 8k video.
That does not work for me. Absolutely no content enables 8K quality. All only show 4K quality. Verified the video on my computer plays in 8K, but the TV Q900 only shows it as a 4K option.