To enable hibernation, in addition to creating the swap device and adding the kernel parameter you must add a dracut module and regenerate the initramfs. See this post, for example:
Just to clarify what hibernation does: when you trigger hibernation, the computer takes the entire session that is being held in RAM and writes it onto the hard drive. Then the computer completely shuts down. When you power the computer back on, it will read the session that was saved on the disk back into RAM and attempt to restore the session.
It is not the same as suspend, which is more of an “idle” state where the monitors and other peripherals may turn off, but the computer stays on and when you move the mouse or whatever it comes right back.
This is what I was trying to say: setting up hibernation will not fix the issue with suspend, it just enables a completely different power management state.
I don’t want to derail the discussion, but if we can just backtrack for a moment:
One explanation for this is a kernel change may have introduced a regression. This is actually fairly common. A quick, simple thing to test will be to install the LTS kernel and see if the issue persists when you boot with it.
sudo pacman -S linux-lts linux-lts-headers
After you reboot, you should be able to select the LTS kernel from the advanced boot options in the Grub menu.