[6.9.2] WebGUI reports inaccurate free space (btrfs)

shfs            8.2T  4.7T  3.6T  57% /mnt/user

3 disks + Parity:

root@unraid1:/mnt/user# btrfs fi df /mnt/disk1
Data, single: total=1.88TiB, used=1.87TiB
System, DUP: total=8.00MiB, used=224.00KiB
Metadata, DUP: total=3.00GiB, used=2.42GiB
GlobalReserve, single: total=512.00MiB, used=32.00KiB
root@unraid1:/mnt/user# btrfs fi df /mnt/disk2
Data, single: total=1.37TiB, used=1.37TiB
System, DUP: total=8.00MiB, used=176.00KiB
Metadata, DUP: total=2.00GiB, used=1.75GiB
GlobalReserve, single: total=512.00MiB, used=0.00B
root@unraid1:/mnt/user# btrfs fi df /mnt/disk3
Data, single: total=1.37TiB, used=1.36TiB
System, DUP: total=8.00MiB, used=176.00KiB
Metadata, DUP: total=2.00GiB, used=1.74GiB
GlobalReserve, single: total=512.00MiB, used=0.00B

Reports ~4.7Tb used, yet the GUI is showing 5.09 used as per image.

That's quite a big difference.