Also, like, language learning apps suffer from the same problem as dating apps: if these apps could actually teach you a language, you'd eventually get proficient enough at the language to no longer need the app — and if you no longer need the app, then it can't harvest your data or subscription money anymore, and line goes down. So the app always needs to give you the impression that you're making progress, while actually sabotaging your learning at every step.
This isn't to say that these apps don't have a place in the language learning process, but rather I'm saying that you need to be incredibly wary not just of the privacy issues, but of how to actually use these apps effectively. If you're aware of their tricks, then they become less effective.