Your not alone, Victor. I tried to watch a 4K 60fps HDR video of Costa Rica and I'm maxed at 1440p on my Note10+. Still, it's the native resolution of the phone itself, so I'm not complaining.
1440P is a resolution of 2560x1440 and not 3040x1440, or better said 4.377.600 Vs 3.686.400 pixels which is a difference of almost 20%
meaning that a cropped/full screen zoom 2160P playback would increase the picture quality...
That said, I'm sure it's a limitation of the YouTube implementation and not related to the Samsung specifically.