GParted 0.25.0 --enable-libparted-dmraid --enable-online-resize

Libparted 3.2

Shrink /dev/sdb1 from 2.73 TiB to 1.42 TiB  00:00:00    ( ERROR )
    
calibrate /dev/sdb1  00:00:00    ( SUCCESS )
    
path: /dev/sdb1 (partition)
start: 2048
end: 5860466654
size: 5860464607 (2.73 TiB)
shrink file system  00:00:00    ( ERROR )
    
btrfs filesystem resize 1:1529581568K /media/marcel/Backup Marcel Waldvogel  00:00:00    ( ERROR )
    
btrfs filesystem resize: too many arguments
usage: btrfs filesystem resize [devid:][+/-]<newsize>[kKmMgGtTpPeE]|[devid:]max <path>

Resize a filesystem

If 'max' is passed, the filesystem will occupy all available space
on the device 'devid'.
[kK] means KiB, which denotes 1KiB = 1024B, 1MiB = 1024KiB, etc.

========================================