The EU Court ruled that “Backdoors may also be exploited by criminal networks and would seriously compromise the security of all users’ electronic communications. The Court takes note of the dangers of restricting encryption described by many experts in the field.” Any requirement to build in backdoors to encryption protocols for law enforcement agencies could also be taken advantage of by malicious actors.
The EU Court of Human Rights’ also builds on their acknowledgment that “mass surveillance does not appear to have contributed to the prevention of terrorist attacks, contrary to earlier assertions made by senior intelligence officials.”
I think the idea is that only the big platforms have to offer a protocol for interoperability You could always disable that in matrix or chat with someone on another chat protocol unencrypted.
But the real advantage is that someone on those big chat apps can just switch to a different (more secure) app without loosing his contacts. Basically this should be a huge boost for open source and trustworthy messaging apps. At least from what I’ve read here:
https://www.eff.org/deeplinks/2022/04/eu-digital-markets-acts-interoperability-rule-addresses-important-need-raises