Cryptomator using up almost entire disk but actual disk usage is tiny

I have a Cryptomator vault on macOS Sonoma which is around 50 GB. I sync it using Dropbox but I have the whole vault downloaded locally. For some reason it’s reported as 1.91 TB but actual data usage of the raw vault before it’s mounted is like 50 GB…

adam@Adams-MacBook-Pro / % df -h
Filesystem                                    Size    Used   Avail Capacity iused ifree %iused  Mounted on
/dev/disk3s1s1                               1.8Ti    12Gi    78Gi    14%    404k  821M    0%   /
devfs                                        302Ki   302Ki     0Bi   100%    1.0k     0  100%   /dev
/dev/disk3s6                                 1.8Ti   3.0Gi    78Gi     4%       3  821M    0%   /System/Volumes/VM
/dev/disk3s2                                 1.8Ti    11Gi    78Gi    13%    1.6k  821M    0%   /System/Volumes/Preboot
/dev/disk3s4                                 1.8Ti   637Mi    78Gi     1%     314  821M    0%   /System/Volumes/Update
/dev/disk1s2                                 500Mi   6.0Mi   480Mi     2%       1  4.9M    0%   /System/Volumes/xarts
/dev/disk1s1                                 500Mi   6.2Mi   480Mi     2%      34  4.9M    0%   /System/Volumes/iSCPreboot
/dev/disk1s3                                 500Mi   3.0Mi   480Mi     1%      88  4.9M    0%   /System/Volumes/Hardware
/dev/disk3s5                                 1.8Ti   1.7Ti    78Gi    96%    3.3M  821M    0%   /System/Volumes/Data
map auto_home                                  0Bi     0Bi     0Bi   100%       0     0     -   /System/Volumes/Data/home
/dev/disk3s7                                 1.8Ti   4.2Gi    78Gi     6%    1.7k  821M    0%   /Library/Synology/ActiveBackupforBusiness/ActiveBackupforBusiness_Reserved
/dev/disk2s1                                 5.0Gi   1.7Gi   3.2Gi    36%      62   34M    0%   /System/Volumes/Update/SFR/mnt1
/dev/disk3s1                                 1.8Ti    12Gi    78Gi    14%    404k  821M    0%   /System/Volumes/Update/mnt1
//Guest:@fuse-t-0._smb._tcp.local/Datasets   1.8Ti   1.7Ti    78Gi    96%    467M   21M   96%   /Users/adam/Library/Application Support/Cryptomator/mnt/Datasets

Any help or ideas? I recently also installed a Synology backup tool which I believe does a snapshot/image in macOS (ActiveBusinessBackup). I think it could be related to that. I should have over 1 TB of free disk space, not 80 GB…