Hello Herb Woman, I think you mean that many of your onion bulbs are swelling below the membrane, while their leaves are growing in full light above?
That is fine, and I guess its from planting through small holes.
To harvest, you may need to ease the membrane off, maybe in 2-3 weeks when the tops are dying down.
That avoids cutting larger holes, to pull out the bulbs. Membrane makes many threads when cut, it best holed with a blow torch which seals the cut edge.
Then use the same holes next year.
Well done on growing no dig without realising!
