iXsystems, makers of a turnkey system installation designed for NAS
servers, announced close to a month ago that they were changing the
emphasis in their product development from “TrueNAS CORE” (which is
FreeBSD-based) to “TrueNAS SCALE” (which is Linux-based, specifically
Debian-based)
<https://www.theregister.com/2024/03/18/truenas_abandons_freebsd/>.

This article
<https://blocksandfiles.com/2024/04/08/ixsystems-no-one-is-getting-marooned/>
gives some more background on the move:

Kris Moore, SVP for engineering, told us: “Upstream has shifted. So
first of all, ZFS, that’s kind of the heart and soul of TrueNAS and
was for FreeNAS as well. Most of that [development] work takes
place on Linux these days; features testing, all that happens on
Linux. FreeBSD is the thing you port to and you’re done. So that
momentum has moved.”

...

“We had a huge chunk of our engineering staff spending time
improving FreeBSD as opposed to working on features and
functionalities. What’s happened now with the transition to having
a Debian basis, the people I used to have 90 percent of their time
working on FreeBSD, they’re working on ZFS features now … That’s
what I want to see; value add for everybody versus sitting around,
implementing something Linux had a years ago.”

The irony in that is, ZFS was deliberately released by Sun (now Oracle)
under a licence that is designed to be incompatible with the GPL that
covers the Linux kernel. If you want to argue otherwise, consider that
Oracle still refuses to include ZFS with its own Linux distro,
preferring to offer you btrfs instead.

Of course, you could also view that as a sign of a lack of confidence in
its own home-grown filesystem ...