What would you do that, they start with open source app, make the online is mandatory and once it’s established and mandated, then they closed source the app and implement data collection?
There is no guarantee that the app would stay open source and under public scrutiny forever. Governments have done way shady things in the past. Given the recent push for chat control, I would never trust anything put out by EU.
I agree that governments should minimize collection of their citizen's data. I just don't see where it is supposed to happen in this case.