I have the Ryzen 5 4600H in my laptop with the R5500M GPU.
I'm guessing that the 128 nvme drive is where Windows is installed. If all of your gaming software is installed there also it could be running short of space. Each game stores a lot of data and info in your "user / app data" folder in windows. I have 13 partitions, some up to 300GB and only one is under 200 GB because it only serves as my Windows cache drive.
If your problem has recently started and gets worse as time passes, the drive space is the first thing that I would check.
I use 250 GB - 300 GB partitions for Windows on all of my machines, even those running Win 7.
I don't think the PSU is your problem, but I have always spent the extra $25 - $50 for a larger (600 - 750W) Corsair.
Sometimes the chipset drivers get corrupted by Microsoft updates. So try uninstalling GPU graphics drivers one more time but this uninstall the chipset drivers also, then power down, not a restart but do a cold system start. Reinstall latest chipset drivers then gpu drivers. If your running some of the newer games make sure you have the latest drivers from AMD not Microsoft and disable automatic updates.
If it ain't broke; don't fix it!