Intel's own version of their USB4 controller
might not support it either.
Absolutely nobody I know has been able to get a straight answer out of anyone; not Intel, not the USB IF, not other members of the USB IF, on if existing Thunderbolt 3 devices will work on USB4 hosts.
And it will be a complete and absolute shitshow if it doesn't, because Type-C has swindled us into thinking Type-C is just Type-C.