An international law enforcement operation has taken down Matrix, an encrypted messaging service used by criminals.

French media mainstream relay the propaganda of the cops, telling that the interception has been made with "innovative technology", but without any details. They also telling that :

European authorities have dismantled Matrix, an encrypted messaging platform made by criminals for criminals. https://cybernews.com/cybercrime/authorities-take-down-matrix/

An expression found in other media; it may be communication from cops.

Do you have any idea how that has been possible ? Do you think they may be issue with matrix or some of the softzare that implement it ? Or do you think that cops compromise terminal (phone or computers) ? I'm more and more suspicious with open network, that let organization enter into the federation, and let it intercept communication.