I've had to abandon the mouse that came with the Raspberry Pi 400 that I purchased some months ago. It was never quite right, especially when it came to copying and pasting, and proved absolutely hopeless when playing online chess because it led to frequent mouse slips. I guess they added the cheapest mouse available to the package. "DESIGNED BY XIAOMI" is printed on the top cover of the mouse, not that it means anything.
It not a big deal as a wireless mouse, especially with its own proprietary dongle, can be bought very cheaply nowadays. Overall, I'm quite happy so far with the performance of this particular Raspberry Pi model. My only complaints have been directed at the deficiencies of the Chromium web browser.
Here is a description of the product taken from the manufacturer's website: