Many reasons: 1) lack of marketing, 2) I stopped working on it for a while, 3) because of #2, the app lacks new features to attract users.

Another one but turned out it was never really a big deal: some chatbots from frontier AI labs started to support those niche features (people still coming to my app for the flexibility of using multiple AI models).

I think the biggest problem was #2, life kept pulling me the other way.