That is not what the law is about.
It is client side scanning embedded in the apps themselves. Each app will have to deploy their own mechanism to intercept the messages. This is not (yet) an OS level scan so there is no AI bot watching your moves on your device yet. Furthermore the AI part will run on their own servers, not on the device.
Precisely, the way it has been described, is when you hit the send button, it will the send the message in clear text to the authorities and then send the encrypted message to the recipient, hence the stupid narrative from the proponents of Chat control that it does not break encryption because it was never encrypted in the first place.
That seems like it will be largely useless. Sure, the masses will continue using a bugged WhatsApp. But anyone with actual interesting/llegal things to say will switch over to an open source messaging app that hasn't been bugged.
That is just the first step of the plan. First they compromise the messaging apps, then they'll make it harder to install open source apps. Then they will force OS level monitoring which is exactly what North Korea does.
This is a power grab pure and simple.
Windows Recall is just the proof of concept and boiling the frog on what's to come later down the road.