Does Manjaro support Wifi on this
MSI Performance Gaming AMD Ryzen 1st, 2nd, and 3rd Gen AM4 M.2 USB 3 DDR4 HDMI Display Port Mini-ITX Motherboard (B450I GAMING PLUS MAX WIFI) ?
I would be very careful with onbard wifi provided by AMD - they are often based on chipset which has poor support on Linux.
Please search the linux hardware database as you will have much better information available.
Thi is for a sys I built for fun really.
There is no fun in unsupported hardware - only challenges and more grey hair - perhaps even losing it due to hairpulling.
Odd AMD open sources GPU drivers, thought WiFI would be the same.
Try this maybe? Liquorix is a great kernel and might solve your problem
curl -s ‘https://liquorix.net/install-liquorix.sh’ | sudo bash