To boot into a BTRFS snapshots from rEFind boot manager.
Additional Info:
So, apparently, to restore the BTRFS snapshot of a root subvolume, I shouldn't do it with the root partition being actively used.
So, I need to boot into the desired snapshot from the boot manager itself.
GRUB has grub-btrfs, which lets you boot into snapshot from OS selection screen itself.
rEFInd has refind-btrfs, which should do the same as grub-btrfs. But it didn't in my case. I am not seeing any way to boot into a snapshot from rEFInd.
I use BTRFS Assistant with snapper to manage snapshots.
I am not seeing any way to restore the snapshot from live environment too.
I am using CachyOS (Arch) with Plasma DE.
I suspect the reason is my unusual /efi/boot partition layout. (attached below)
I did my partition this way because, my initial EFI partition had less storage (as seen on image), so , I created another boot partition and mounted my pre-existing EFI partition to /boot/efi. I did this by referring a Youtube video (I know, I should've known better)