https://www.theguardian.com/technology/2021/sep/08/facebook-encryption-could-prevent-detection-of-child-abuse-nca-says

Police claim plans for end-to-end encryption will stop officers being able to access ‘incisive intelligence’

Facebook’s plans to allow encrypted messaging across all its platforms could prevent the detection of up to 20m child abuse images every year, a senior investigating officer has claimed.