When you publish a serial on Substack, this is what it tends to look like. Not surprising at all (this was not my first rodeo, so to speak), and it’s obvious you lose some readers along the way + no one is going to start with parts two or three. But still.

It may also be that the story isn’t strong enough, that would be my first guess. It’s just that I’ve seen this pattern every time I’ve tried a serial. I don’t know if there’s a way to change it, though. I imagine Amazon sees a similar trend in novels on Kindle.