I have 1.9k views on WEBTOON, and 106 subs. So, about half the retention rate you have.
That said, I was posting it in comic page format until a few days ago, which would have put mobile readers off. Plus, I also advertise each new page on Reddit, which means a trickle of new people coming to have a look, but not necessarily subscribing.
It is a bit demoralising, realising so many people have looked/read your work but not felt compelled to subscribe! But not every story is to everyone's taste, and there's a multitude of perfectly understandable reasons why a person might not be into the story you're telling, which don't reflect at all on the quality of your work.
Your comic is awesome, by the way! I subbed to it when I stumbled across it a couple of weeks ago. I'm a total sucker for the combination of a high-tech setting with magic. My own setting is like that, too. 