This is possible, but I don’t recall anyone else having this problem. I think your last update was in December, I’m not sure what we changed at the time. I can’t see anything related in the release notes. Do you remember when it was still working?
I just looked in the database and Leafy Greens are still a child of Vegetables.
Now I checked our staging server and our production server and they have the same problem, only the root taxonomies are shown, no child taxonomies.
You may have found a new bug. Actually, I had a look and Kirsten discovered this in Taxonomies / Product Categories broken · Issue #1965 · openfoodfoundation/openfoodnetwork · GitHub. Unfortunately, it got marked as fixed without proper testing (it looks like). From the comments, I would guess that this broke in the last Spree upgrade.
I think you should create a new issue on Github. The last one was rated s3.