Correct.

The 1st century started at 1 A.D. and included 100. 2nd century started 101 to 200. Etc etc. If you change the 21st century to be 2000. You would to shift everything down. Eventually making the 1st century 99 years. Or creating a year 0 or using 1BC.

You can go higher that 4k@60 but youll be using chroma subsampling. Which can make text look really bad.

https://www.rtings.com/tv/learn/chroma-subsampling

This is the correct answer. Using my 6900XT, I can’t run a 4k120hz display over HDMI without subsampling.

This hopefully will change with the new AMD GPUs, but that’s wishful thinking.