“4K UHD cables are ultra high speed. HDMI 3.0 IIRC. Carry a lot more signal(s) than original spec cables.”
The are all. the same “speed’.
There is no 3.0 standard.
The mods are not with the cables but with the electronics.
I am running my 4k UHD TV using. my same old cables.
You’re right. I was mixing up USB and HDMI specs. 2.1 is the Current HDMI spec. As for cables... https://www.hdmi.org/spec21Sub/UltraHighSpeedCable
For 4K and higher resolutions, Dolby ATMOS audio, eArc etc., you really want newer HS spec’d cables.