Yes, I totally agree!! Something that really bugs me especially is that the happy ending (minus the last like 20 seconds, obviously) feels so forced. It’s the True Pacifist ending, but minus all of the thought and care that went into achieving it in Undertale. It also feels quite premature since this is only supposed to be chapter one.
I think the game as a whole has a very strong undercurrent of a happy exterior with a very dark interior. Something about it is deeply unsettling, but you can never quite pin down what it is.