For you using Grub and Btrfs with encryption
$ cryptsetup luksOpen /dev/nvme0n1p2 my_encypted_device
$ mount /dev/mapper/my_encypted_device -o subvol=@ /mnt
$ mount /dev/nvme0n1p1 /mnt/boot/efi
$ mount /dev/mapper/my_encypted_device -o subvol=@log /mnt/var/log
$ mount /dev/mapper/my_encypted_device -o subvol=@cache /mnt/var/cache
$ mount /dev/mapper/my_encypted_device -o subvol=@home /mnt/home
$ manjaro-chroot /mnt
Then follow: