HDMI 2.1 has a variable refresh rate mode which will presumably become the standard over time.
The DVI and HDMI protocols doesn’t need anything specific to support variable refresh rate: nothing prevents one to just extend the vertical front porch time.
It’s just a question whether or not the GPU can generate that kind of signal and whether the monitor scaler chip is willing to deal with it.
Also, it's very interesting that things are so different in France with regard to display cables. I would've assumed that, since it's mostly the same manufacturers making everything around the world, they'd have more or less standard models across regions.