Today, HDMI 2.0 and all previous HDMI versions use TMDS.

Transition-minimized differential signaling (TMDS)

HDMI 2.1 does not use TMDS. It uses the new FRL encoding scheme

FRL (Fixed Rate Link) is a high-speed data transmission encoding scheme used in HDMI 2.1 that replaces the older TMDS (Transition-Minimized Differential Signaling).

https://www.blackbox.com/insights/blogs/detail/tps/2021/02/03/new-hdmi-2.1-technology-part-1-of-2