Protecting children online is a priority for the EU legislator. Since July 2021, an interim regulation allows service providers to derogate from confidentiality safeguards in the e-privacy Directive to fight child sexual abuse online. The European Commission aims to repeal this legislation with a proposal of May 2022. This Regulation will require providers to monitor users' content communication for online child sexual abuse, among other things. Privacy experts worry that confidentiality standards (i.e. end-to-end encryption) will be weakened and that the Regulation will serve as a basis for indiscriminate interception of content communications. However, the implications of the proposal go beyond privacy and data protection and will impact criminal justice rights too. Therefore, this contribution presents a comprehensive analysis of the proposal from a privacy, data protection and criminal justice perspective. It examines the proportionality of the measure and its implications within the Area of Freedom, Security, and Justice (AFSJ). Specifically, it looks at purpose limitation issues in data exchanges and the admissibility of such evidence in criminal proceedings. The aim is to show that the EU, while aiming at increasing data circulation in the AFSJ, might not be ready for this challenge from an infrastructural and fundamental rights standpoint. [ABSTRACT FROM AUTHOR]