This has always been possible.
Here’s a thread, in which the culprit was the network card.
Here’s another thread of a similar issue, in which SMB was the culprit.
This can also happen with interrupted or incomplete downloads. You’ll see that the image can be viewed from the top, until it hits a point in the JPEG where there is no more image data.
ZFS is actually working correctly. The image, as it “corruptly” exists with its blocks on the storage drives, was checksummed and then written by ZFS. The “corrupt” image file is the “correct” data, according to ZFS or any data integrity tools that confirm what has been initially written to disk.
ZFS can only protect your data against corruption after it has already been written to storage. There’s nothing it can do beforehand if the data is ruined by a bad NIC, bad RAM, or buggy software, such as SMB.