Who is downvoting this? Among the large Linux distributions, ZFS is only really supported by Ubuntu, and even that is on the level "Canonical lawyers reviewed this and believe they're safe". If the unmentionable company ever goes to court against them, you're in hot water. You'll have to migrate to FreeBSD or support yourself by building dkms modules. So you're taking a non-zero risk by adopting ZFS.
If you're really conservative with these things, as some of us are, you currently don't really have a single safe COW pick. (Smug FreeBSD users incoming.) I have most trust in bcachefs over the long term.