"Chat Control" is mass surveillance, not targeted Action. Targeted action mayhaps needs some readjustment, but by and large is already easy to obtain for law enforcement.

Normalizing mass surveillance would set a precedent for authoritarian regimes worldwide to demand similar access, further eroding privacy and human rights on a global scale.

I also oppose it on technical grounds, since it would be some kind of local or hybrid ai that does the scanning. A high number of false positives harming innocents would certainly be the result.