those "@_backup_..." actually appear in btrfs subvolumes for me and they are the reason of extra "Garuda linux on /dev/nvme0n1p2". Deleting them and then updating grub with
sudo update-grub
has been the solution for me and several people. They are created by snapper when you roll back a snapshot.
To delete those backup subvolumes using the btrfs assistant is the easiest method to achieve it.
