Years ago i saw someone do a breakdown of what you’re talking about and if memory serves it’s the Herb episode that changes the vibe of the show. Until that point bojack feels like every other crude comedy on air but from that point on it breaks the traditional format. Its the first time on screen, and possibly in bojacks whole life(outside of family issues), that he faces consequences for his actions that have a serious negative impact on him and the fix is out of his control. In the face of this truth he spirals into a world of indulgence and avoidance and we the viewer begin to see the impact that has on those around him.