In a support document published earlier this week, Apple made some clarifications about potential problems that some USB hubs can cause when connected to their computers. Typically used to expand the number of peripherals that can be used on Macs, these accessories can cause instabilities in the operating system if they do not support their boot sequence or are being used incorrectly.
By default, Apple does not recommend that one USB hub be connected to another, so this would be an incorrect example of using them. Another example would be the connection of a hub to one of its monitors, which are already connected to computers using the standard Mac OS X peripheral boot sequence. There are users who also use wireless mice and keyboards with a USB extension connected only machines, which can cause instabilities, crashes and even the disconnection of other devices in use when used to take the computer out of sleep.
To avoid serious problems, Apple recommends that external HDDs and SSDs are always directly connected to computers, so that data loss is avoided. In addition, it is recommended to take your Mac out of sleep using the outside button or the integrated keyboard of your notebook, in case the mouse you are using is connected to a USB hub or depends on a separate device connected to the computer to operate wirelessly.