May be related to not being able to monetize 4k (https://9to5google.com/2022/10/17/youtube-premium-4k-test/ https://9to5google.com/2022/10/17/youtube-premium-4k

May be related to not being able to monetize 4k (https://9to5google.com/2022/10/17/youtube-premium-4k-test/ https://9to5google.com/2022/10/17/youtube-premium-4k-test/), so they just charge more.