Trying taking the "Requires=btrfs_backup.service" out of the timer.
the man systemd.unit page says Requires will activate the requirements as well So activating the Timer activate the requirement of btrfs_backup.service
Trying taking the "Requires=btrfs_backup.service" out of the timer.
the man systemd.unit page says Requires will activate the requirements as well So activating the Timer activate the requirement of btrfs_backup.service