The MacBook Pro, Mac Studio and Mac Pro all have Thunderbolt 4 ports. The MacBook Air only advertises its ports as USB4/Thunderbolt 3, though.There are few devices I know of that support USB 4.0 or Thunderbolt 3.0. Even 20 Gbps is sufficient for most data transfer needs.
The specs are somewhat meaningless here though if you aren't manufacturing cables or devices. As a consumer, you should use a 40 Gbps cable to connect two 40Gbps devices - and you're going 40Gpbs.
The issue is that nobody is using the USB marks here, and there's not much else to help you troubleshoot slowness when the marks aren't on the devices/cables.