ANSWER:

  • A USB flash drive with a Type C connector is, in most cases, compatible with a Thunderbolt 3 port and in all cases with a Thunderbolt 4 port.


RATIONALE:

  • Both the Thunderbolt 3 and 4 standards specify backward compatibility with USB 3.1 gen 2 and therefore all previous USB protocols, but there is wiggle room in the Thunderbolt 3 standard (ie. may support... provisions, and therefore may NOT be fully backward compatibility with all USB devices.
  • The Thunderbolt 4 standard, on the other hand, requires compatibility with USB 4 and the USB 4 standard, in turn, requires backward compatibility with all previous USB protocols.


EXPERIENCE

  • I have run into a couple of cases where connecting a USB 3.1 Gen 2 disk drive to a Thunderbolt 4 port using a Thunderbolt 3 cable was not successful. Replacing the Thunderbolt 3 cable with a Thunderbolt 4 cable solved the connection problem.
  • A port converter is technically a very short length of cable.

If we knew what it was we were doing, it wouldn't be called research, would it?

— Albert Einstein