There's a growing concern that "bad-actors" are amassing troves of encrypted data, and storing it away for possible future decryption using quantum computers. Many services have put in efforts to make certain that their encryption algorithms are "quantum-safe", so as to protect against such attacks. Has Matrix done the same?
Last I’d heard, even the NSA hasn’t been able to find an encryption that is quantum safe. And the some of the one they had found were broken using traditional computers. I strongly suspect that your messages will remain reasonably private for at least the next decade or two.