I don't know if this has changed since I last looked a few years ago (around 2018-2019), but: The app-signing key can't be changed without just creating a new

I don't know if this has changed since I last looked a few years ago (around 2018-2019), but: The app-signing key can't be changed without just creating a new app, and creating a new app means you users won't be able to upgrade - they have to manually uninstall, go to the app store, and install the new one. It's not just an app store thing, I think I remember Android itself verifies that the upgrades have the same key as the old version.