Comment by thatcks

Two examples that I can find are https://github.com/openzfs/zfs/issues/7910, where very old versions of ZFS appear to have quietly written slightly incorrect ACL information, and https://bugs.launchpad.net/ubuntu/+source/zfs-linux/+bug/190... where Ubuntu 21.10 shipped with a bug that created corrupted ZFS filesystems. I believe https://www.illumos.org/issues/9847 may be another example of this, although less severe, where ZFS leaked disk space under some circumstances.