Some components of our apps are open-source, but the main apps are not. This is to protect you and us from unscrupulous counterfeiters who add malware and ads to open-source apps.
I am not following these claims carefully, but I have seen tons of copies of Lawnchair in the Playstore.
Another recent event that comes to my mind is the Simple apps, which AFAIK they always were open source? But that didn't matter until it got sold and then Fossify was the non shit version of it (the positive side of open source).
We have seen time and again, especially on Android, that whenever a moderately-popular app goes open-source, it is immediately picked up by unscrupulous developers. They download the source, add obnoxious ads [...]. tracking code [...]. Finally, they publish it to the Play Store
This is a pretty bad argument, especially when you're specifically talking about Android. Android APKs are extremely easy to just download from closed-source, decompile them, and add new things or overwrite existing things.
The argument makes more sense for things that are harder to decompile and recompile