The accelerated pregnancy doesn't actually bother me THAT much. Sure, it's pure fantasy and a bit stupid, but it solves a common issue of otherwise "locking" a character in pregnancy mode for probably the entire story otherwise (another solution is obviously time skips, but it doesn't work in every story).
What bothers me far more is the birth scene and the "baby" being some Looney Tunes level of silly, which came completely out of left field.
I'll add my voice to those saying that retconning this as a bad dream might be the only way to salvage this. And then maybe make it so, yes, the serum works but instead it just cuts pregnancy time in half. That way it would give the MC time to get everyone pregnant and after a while when every girl being pregnant gets boring the game can do a short time skip, and it turns out the girls gave birth to normal, healthy babies instead whatever that thing I wanted to throw into a woodchipper was.
