The other comments already covered this, but yes, that is arguably the correct use of features: only enable the features (many of which can only be set at file

The other comments already covered this, but yes, that is arguably the correct use of features: only enable the features (many of which can only be set at file system creation time; others can be upgraded to in a one way direction) that are supported by your target hosts. At the time you last ran it (also said by sibling comment), FreeBSD still had not yet ran upstream OpenZFS, and still ran their own older code. To have had FBSD compatibility at the time, you would have had to only enable the features FBSD supported. Generating the file system on FBSD, and not running "zfs upgrade" on Ubuntu would be one way of doing this, to avoid having to manually set features at all. Today this is not an issue, everyone runs the same code.