As with most first posts here, concerning anything…
very little machine and specific configuration info is provided. What machine are you using? How is it configured? (RAM, cards installed, etc.)
First, what version of USB is the thumb drive? Second, was it initially formatted using the machine you’re trying to access it with? Third, why aren’t you running OS 9.2.2?
With limited info, I’d first suggest reformatting the thumb drive using the 9.1 machine. Then, if possible… I’d also update system software to OS 9.2.2 (if not doing this first).
See the following for USB version differences:
http://techdracula.com/difference-between-usb-1-0-usb-1-1-usb-2-0-usb-3-0-usb-3-1-usb-type-c/G4s are USB 1.1 / but with an additional card, I know that (at least), USB 2.0 read/write transfer rates are achieveable. Of course, you may already know all of this but I’m just ‘shooting from the hip’ here… not knowing more about your machine or specific file types.
AND, with the slowdown in “low power mode”… you may have some other concern(s) as well.
Good luck.