Ever since I wrote It's Time For Furries to Stop Using Telegram, I've had a few folks ask me about my opinion on Matrix.
(I've also had a few people evangelize Matrix in my mentions. That's annoying.)
My stance on Matrix has been the same for years: I don't trust the Matrix developers to produce a secure protocol, and until they abandon Olm / Megolm in favor of something like MLS, I'm adamant about refusing to trust their team's designs.
To understand why I feel so strongly about this, you need to understand that practically exploitable vulnerabilities were found in Matrix in 2022.
It isn't enough that there were vulnerabilities found to be alarming. Vulnerabilities happen. You aren't writing software if you don't occasionally fuck up.