From iXsystems community: https://www.ixsystems.com/community/threads/unexpected-automatic-daily-snapshots.81986/
I had custom snapshot tasks on all of my datasets to create a daily snapshot at 23:00.
After the upgrade to 11.3 i decided to change them to the standard daily task that runs at 00:00.
Ever since the change i see the expected snapshots at 00:00 but another at 04:15 for every dataset.
I've tried deleteing the scheduled task but the snapshot at 04:15 is still created.
Anyone have an idea how i can stop these additional snapshots being created?