External Hard Drive Faster when connected via Studio Display

I'm running a MacBook Pro M1 Max connected to a Studio Display via the standard Apple Thunderbolt cable. I also use a bunch of hard drives in a Terramaster enclosure which connects via a USB 3.2 (Gen 2) port.

When I plug the enclosure into the Studio Display's USB 3 ports, I get speeds of up to 130MB/s on a single drive, and 250MB/s if I combine two drives into a RAID 0 setup. But if I connect the enclosure directly to the MacBook Pro's USB ports I get only about 30MB/s.

Same cable same hard drives, same enclosure. Any idea what's going on?

MST