I was told that "as soon as the user is in the audience, they will always be in this audience." I am curious how long "forever" in the context of the user? For example, if a user changes phones or uninstalls an application, and then reinstalls later, is the user saved through these transitions, or is each of them a separate user? And if I have several applications in one Firebase project, does the user appear in the same audience in all applications of this project?
What does Firebase Analytics consider a unique / new user?
One precedent that I want to try with the Audience is to have an audience of "existing users" (defined by "first_open_time <= {some date}") and "newer users". I have some changes that I want to implement for new users, but I want existing users to have "deprecated" behavior for a while, moving them slower. If someone was present in the audience of the "existing user", then received a new phone or deleted, and then installed the application again, suddenly they will become a new user and, therefore, will no longer be in the audience of the "existing user"?
Another use case: I have an existing application, and I am writing a completely new application that will have a new package name, and therefore will become a new installation for all my existing users. I want all of them to be transferred to the new application for free, and the best way I can do this is to have both the old and the new application in one Firebase project, and also put the users of the old application in the audience and when they launch the new if they are in the audience of "old application users", it will automatically provide them with premium features.
To be sure in any case, I need to better understand the definition of "user" for Firebase - is it not saved through uninstalls, transition between devices and can you share audiences between applications in the project?
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