The FRONT USB-C ports on the Mac Studio Max processor (but not Ultra processor) are limited to nominal 10,000 M bits sec speeds, about nominal 1,000 M Bytes/secs. Actual maximum speeds are more like 800 M bytes/sec.
However, this could be a software problem:
Drives like the MyBook came with software, and the manufacturer suggested you install that software.
What that software does is to "spare you the annoyance of having to re-initialize the drive" from its factory set Windows New Technology File System (NTFS, the W is silent because there are no other Operating Systems) or similar unusual (on a Mac) format. Instead, the software they provided would simulate a MacOS drive inside an NTFS file for your Mac.
The downside of using the manufacturer's software is that if the manufacturer's software is not loaded, the Macintosh Volume may not be readable, or may not be writable. This means that in startup manager, Installer, and in Recovery such as after a data loss, the Macintosh Volume may not be visible.
The standard advice given here to all users, including novice users, is to discard the manufacturers software and NEVER use it. "Best Practice" is to erase the physical device when new, using only MacOS Disk Utility, and create the fundamental data structures needed for consistent, reliable use by MacOS.
Be sure to "show all devices" which will allow you to ERASE the entire Physical Device by its immutable manufacturer-given device-name, not just user created Volume-name such as ‘Macintosh HD’.
