In the app itself, the Discord server, and the GitHub, Amethyst should have a clear, simple clarification to new users that this application is not meant to give out free Minecraft Java.
It should indicate that the app is simply a launcher for the game and that any user needs to already own Java on their account.
This may already be the case, however, making sure that it is nice and clear can never hurt.
This would be especially good, as I have not used Pojav originally for much time at all, and I have already seen my fair share of people thinking they are getting free Minecraft.
Making it clear that this isn't the case will help to clear things up among newcomers and will probably help to keep reputation up.
A simple message on GitHub, a notice in the Discord FAQ and rules, and of course an initial popup or other clear message within the app would be how this can be done.