CSGO should run pretty well on that system, but it's online so lag may be from other places.
The reason laptops have dual video cards is not just for them to work together, it's also for power savings. When you are not playing games it will use the onboard graphics for longer battery life. Dual graphics can be a pain to work with, it often depends on the stock setup of the laptop, with drivers from the laptop vendor. If Microsoft had a driver update or if you tried to install the drivers from the video card maker, that can break proper use of dual graphics with AMD cards.
I'd check with support for the laptop and see if things are working the way they should be.
You can also do a test by disabling the gaming video card in Device Manager and running the game, then again when it's enabled and see the difference.