My laptop is running Windows 10 with the stated processor above. It has AMD Adrenalin 2020 install and is on the latest driver update. When I attempt to play games on full settings, such as Portal 2, I well get 60 to 100 fps while on battery and not charging; However, when I have the charger plugged in, the GPU limits itself to 300Mhz causing my framerate to be 16fps or less.
Maybe you have set it to have the best battery life while plugged in. Go to the bottom right of your screen and find a battery icon. Click on the battery icon change it to best performance while your computer is plugged in.