Timeshift and BTRFS subvolume's naming

Does Timeshift subscribe to a certain naming convention for the root of the file system on BTRFS?

In two installations on BTRFS / is @ and launching Timeshift, it defaults to BTRFS and I am able to make snapshots.

In two others, one Fedore with / simply root and another Arch with / named @arch-budgie-root (would actually like to change the name since it is converted to KDE Plasma soon after the installation), when I launch Timeshift, it defaults to Rsync. Upon choosing BTRFS in the wizard, the whole application crashes.

Using the CLI, results in the following output which is quite bizarre. It defauls to /dev/nvme0n1p2.
That is Fedora’s /boot :sweat_smile:

sudo timeshift --create 
[sudo] password for pebcak: 
First run mode (config file not found)
Selected default snapshot type: RSYNC
Mounted '/dev/nvme0n1p2' at '/run/timeshift/backup'
Selected default snapshot device: /dev/nvme0n1p2
------------------------------------------------------------------------------
Estimating system size...
Creating new snapshot...(RSYNC)
Saving to device: /dev/nvme0n1p2, mounted at path: /run/timeshift/backup
Synching files with rsync...
E: rsync returned an error                                                      
E: Failed to create new snapshot
Failed to create snapshot
------------------------------------------------------------------------------
Removing snapshots (incomplete):
------------------------------------------------------------------------------
Removing '2021-08-14_14-53-46'...
Removed '2021-08-14_14-53-46'                                                   
----------------------------------------------------------------------`Preformatted text`

Does anyone know what the issue might be and how to work around it?