I have the same issue with my Thinkpad E595 running a Ryzen 5 3500U. I have tried all the latest kernels : 5.4 and up. I even tried installing Linux Mint, thinking the kernel version they are using would have that problem solved. It seemed to work without issues from a live USB for hours, so I thought it worked, but turns out it has the exact same behavior now, after I have done all of the updates. I have no issues on my Thinkpad T420 (i7-2720QM), which is also running Manjaro.