It might be something related to ISP trying to optimize bandwidth during "home office era"...
I was thinking the same thing, but I don't think my ISP would gradually look at every 8K video and disable the 8K option one by one. As I said, the number of 8K videos has decreased over time.
If you are logged in, maybe it's overridden by bandwidth limitation settings on your account.
I tried in an incognito tab and the same exists.
Here's a video available in 8K for me, https://www.youtube.com/watch?v=zf3bDpdhUNc - does the 8K work for you?
Most people are watching them on a phone, and the higher resolution like doesn't matter on a phone.
I am doing on my main PC. My phone isn't capable enough to display anything over 1080p. On the YouTube desktop site on phone, it still give me the option of 4K at max IIRC.
Could be many things, but my money is on something wrong with your browser configuration.
TBH, I don't change much with my browser configurations. I just set the default SE on Edge, install uBlock Origin and TouchVPN, and I am on my way to work.
Do you use Chrome, I could go back there but I don't want RAM eaters anymore.
previously known as Discrete_BOB_058