I'm saying that people put Matrix/Element in competition with Signal. These used to be dominating voices here. I do think the Matrix == Slack and Signal == Text philosophy has become more prominent now (the philosophy I prescribe to). But there are also major discussions about decentralization and users would suggest Matrix was more secure because of that even though at the time group chats were not encrypted (they are now) and E2EE was not enabled by default.

These are purely my observations of the discourse around Signal and should not be taken as a universal truth. Only my subjective reality.

I'm not aware of any major vulnerabilities in Matrix (but I'm not following) closely. I'm also not aware of any in Signal, which I know is frequently audited. There is an SGX attack, but it is often blown out of proportion (highly technical attack that requires an unlocked phone to be in the physical hands of the attacker).