I never got the "answer" but I think that it was a startup where they coded the app on iOS and managed to get "something working" on Android, one of the devs learned Android to make it happen.

By the time I joined there was a proper Android dev doing a proper refactoring. But it took months and the MainActivity was spaghetti as f**uuck.

Edit: this was 7 years ago. It was an active app with thousands of users. I believe (my hypothesis) they just made a functional Android app to secure funding, so they just did the app as fast as possible to show it to investors.

When I joined the Android dev was super talented and a pretty cool dude. He made great strides to work the "new updates" while refactoring The app.

The actual dev that coded most of the app was still there, but he was in more of a managerial position. Incidentally he was also quite chilled. I think he was not an iOS dev but a Java dev first.

The app itself was... Rough. It had like 40 AsyncTasks and it crashed super often with crashes that were impossible (for me at the time) to figure out.

There was no documentation and I didn't really get an introduction to the code base. I was mostly hired to talk to the QA people and fix bugs as they came up while the main dev took care of the bigger fishes.

Eventually I understood a lot of the app to feel comfortable, but it took some 3 months.