I ordered a cheap (~$25) USB-C multiport adapter (USB-A / VGA / USB-C) from Amazon for use with my 2016 MacBook Pro (non-touchbar). When the adapter is plugged in, apps take a long time to quit and very often need to be force-quit. This happens for system apps as well as third-party apps.
Interestingly, this happens regardless of whether anything is plugged in to the adapter. In other words, as long as the adapter is plugged in, even with nothing plugged in to the adapter itself, apps take a long time to quit.
I haven't noticed any other ill effects while the adapter has been plugged in, and have of course tried to reboot, power off/on, etc to no avail.
I understand that a cheap adapter like this one may introduce compatibility issues, and will probably be returning it. However, even if there is not a way to eliminate the issue and keep the adapter, I'd still like to understand what the issue is and what is causing it.
Thanks in advance for your help.