From the review section of that enclosure: > Cons: - Included USB-C to USB-C cable is only capable of USB 2.0 speeds (40 MB/s as measured with crystaldiskmark)

From the review section of that enclosure: > Cons: - Included USB-C to USB-C cable is only capable of USB 2.0 speeds (40 MB/s as measured with crystaldiskmark) yeah, that would explain it.