The installer was still adding the legacy sysctl vfs.zfs.min_auto_ashift=12 to /etc/sysctl.conf until very recently -- commit 87a7b35f04b6 ("bsdinstall: fix vfs.zfs.vdev.min_auto_ashift oid"), and many users have this in sysctl.conf.
Restore the legacy aliases for now, until we can execute on a deprecation plan.
This reverts commit ced72fdd69f27b54cf592351a36660cd9fd7dbd3.