Why is my filesystem shrinking?

Hello,

I am pretty new to FreeBSD and zfs. I have a VM where I have a 12GB Disk for my root disk. But currently the root partition seems to shrink. When I do a zpool list I see the zroot is 11GB

askr# zpool list
NAME    SIZE  ALLOC   FREE  CKPOINT  EXPANDSZ   FRAG    CAP  DEDUP    HEALTH  ALTROOT
zroot  10.9G  10.5G   378M        -         -    92%    96%  1.00x    ONLINE  -

But df show the following

askr# df -h
Filesystem            Size    Used   Avail Capacity  Mounted on
zroot/ROOT/default    3.7G    3.6G     36M    99%    /
devfs                 1.0K      0B    1.0K     0%    /dev
zroot                  36M     24K     36M     0%    /zroot

Now when I go ahead and delete like 100MB zroot/ROOT/default shrinks by this 100MB

askr# df -h
Filesystem            Size    Used   Avail Capacity  Mounted on
zroot/ROOT/default    3.6G    3.5G     35M    99%    /
devfs                 1.0K      0B    1.0K     0%    /dev
zroot                  35M     24K     35M     0%    /zroot

I already tried to resize the VM Disk and then the pool but the pool doesn't expand despite autoexpand being online. I did the following

askr# gpart resize -i 4 /dev/ada0
ada0p4 resized
askr# zpool get autoexpand zroot
NAME   PROPERTY    VALUE   SOURCE
zroot  autoexpand  on      local
askr# zpool online -e zroot ada0p4
askr# df -h
Filesystem            Size    Used   Avail Capacity  Mounted on
zroot/ROOT/default    3.6G    3.5G     35M    99%    /
devfs                 1.0K      0B    1.0K     0%    /dev
zroot                  35M     24K     35M     0%    /zroot
```

I am at the end of my knowledge. Should I just scrap the VM and start over? It's only my DHCP server and holds no impoertant data, I can deploy it with ansible from scratch without issues.