nextboot warns it won't reset

Hi all, nextboot warns as follows:

# nextboot -k testkernel
WARNING: loader(8) has only R/O support for ZFS
nextboot.conf will NOT be reset in case of kernel boot failure


This's on a ZFS zroot 12.4-STABLE system.

Does this mean that nextboot will not do its job?

I see a blog mentioning that nextboot will write metadata to the ZFS pool label,
in which case maybe the warning is no longer applicable?


Also I suspect I should rather run "nextboot -D" to revert the situation.
Is this equivalent to removing /boot/nextboot.conf and/or this metadata in the
ZFS pool label?