This statement is for USB devices that require power to be supplied to it.
The Intel Macs USB Ports were supplying power for those devices, the M1 doesn't supply the required power those USB devices need.
This statement doesn't apply to you because your Korg SQ-64 requires to be plug-in with the AC adapter, which is where the power is being supplied.
For those wanting to get a M1, make sure to do the homework, otherwise expect frustration.
The SQ-64 doesn't require an AC adapter, but yes it's true the M1 doesn't supply the right power, though it still works. On the SQ-64 there are two USB Power settings, 500mA and 2A, with the 500mA for older USB 2.0. The M1 will only supply that amount, because when I switch it to 2A the System Information on the M1 still shows 500mA being sent.
Like I say it still works, the difference is the lights are dimmer. Can't say for sure if other devices work though. My guess is if they don't require much power, over that 500mA, they will work.