Comment by magicalhippo

> Can you give a more concrete example of what you mean?

There's been several instances. For example, the send/receive code has had bugs leading to cases[1] where the checksum and hence scrub look fine but the data is not.

edit: the recent block cloning has also had some issues, eg[2][3].

I'm pretty sure it's also possible for hardware errors like bad memory to cause the data to get corrupted but the checksum gets computed on the corrupted data, thus it looks ok when scrubbed.

[1]: https://github.com/openzfs/zfs/issues/4809

[2]: https://github.com/openzfs/zfs/issues/15526

[3]: https://github.com/openzfs/zfs/issues/15933