Darling has dark undercurrents in general...which seems to be deliberate (thankfully). I don't know what the recent episodes changed but the show has redeemed itself in my eyes...Probably because they toned down the metaphor a bit.
I doubt the conspiracy, but I wouldn't say the show is above social commentary on that point. The main cast is noted as "test subjects" and otherwise marked as abnormal for having something approaching normal human relations, while what little we see of the adults in-series is that they do not care for human contact at all. Wouldn't surprise me if it was a jab at the birthrate.I think I heard a conspiracy theory that Darling is part of a plot to help stimulate Japan's declining birthrate. Which would explain a lot, admittedly.