Hey, I recently switched to Manjaro from Xubuntu 18.04 to keep this old PC usable without having to upgrade any parts, but I noticed something weird, every program seems to use the CPU instead of the GPU for rendering graphics and I can’t find a way to solve this.
Welcome to Manjaro!
Please read this:
How to provide good information
and post some more information so we can see what’s really going on. Now we know the symptom of the disease, but we need some more probing to know where the origin lies…
An inxi --admin --verbosity=7 --filter --no-host --width would be the minimum required information… (Personally Identifiable Information like serial numbers and MAC addresses will be filtered out by the above command)
Kernel 5.9.16-1-MANJARO is EOL, so consider upgrading to 5.4 LTS (Long Time Support) or 5.10 (LTS candidate)
How did you install those??? 
P.S. If you enter a bit more details in your profile, we can also see which Desktop Environment you’re using, which CPU/GPU or Kernel or … you have without you always having to type it…