VGA monitor panel "twitches" between normal and slightly yellow on MacBook but works perfectly on Windows laptop
Solution 1:
It is highly probable that the USB to VGA adapter is faulty.
To be 100% sure that it is the adapter, you would need to test another VGA monitor and a USB to VGA adapter. However, you have demonstrated the monitor works fine without it. That being said, USB to VGA adapters, especially cheap ones, are known to get hot internally and fail. I would replace it and go with a high quality, name brand option if you choose to stay with that method of connection.