Start with protecting children. Then something about misinformation. Then about defending democracy. Then about stopping terrorism. And soon you can escalate your authoritarian policy to just about anything.
This is why having the structure of fundamental civil rights, like in the US constitution, is important. I’m surprised the EU doesn’t seem to have such protections for free speech and privacy and against warrantless surveillance.
Between FISC, the Patriot Act/USA Freedom Act, and such it doesn't seem like the US constitution is doing a good job at protecting anyone. There is a long wikipedia article named Mass surveillance in the United States, but not yet one for the EU.
I wonder what the chances are that the ECJ could look at employing actions for annulment against chat control, if it is passed. It is possible for private individuals to ask the court to annul an EU act that directly concerns them. So even if governmental structures across EU does not want it challenged, the issue could still be brought to the court.