I think the issue was a lot of things being sold in the early days of HDMI 2.1 that claimed full compatibility, but there was so little hardware that actually supported it all that most people had no way of testing. And I suspect all the usual stroke-at-the-keyboard branded Amazon specials just took all the existing HDMI 2.0 kit and stuck new labels on it.
Good to know.
I think the issue was a lot of things being sold in the early days of HDMI 2.1 that claimed full compatibility, but there was so little hardware that actually supported it all that most people had no way of testing. And I suspect all the usual stroke-at-the-keyboard branded Amazon specials just took all the existing HDMI 2.0 kit and stuck new labels on it.