Specs look good and should run CSGO.
I am not really sure why it is slow to be honest. There could be many things causing this. I would suggest to look at GPU drivers, but with the AMD GPU, I believe the drivers are already integrated in the kernel so there's probably no need to reinstall/download GPU drivers. I assume you have the open source AMD driver for Vulkan?
Are there any other apps running on the machine when you're trying to play the game? Have you also looked at the game settings to see if things like resolution, shadows, etc are tweaked for your machine?
I also had performance issues in the past with KDE desktop environment and games seemed to run much smoother for me in Gnome. If you're using KDE, you also might have to adjust the compositor settings to OpenGL 3.1 which should improve the overall experience.