Matrix (as a protocol) appears to be very strong end-to-end encryption and is federated/decentralized. It can do encrypted and unencrypted chats for any number of users, so it can replace discord (which is not at all private or secure) and do private 1:1 communications (which I'd say is the best use case for it). It also does not require a phone number like signal does (which is usually tied to your legal identity and can be used for geolocation).

I wouldn't trust any electron apps, which is the framework the official Matrix client, Element, is built on. It's fully open-source so there are other clients out there which may be better. Of course, the biggest weakness is probably going to be the OS/firmware of device you run it on.

Edit: The desktop element clients rely on electron (which is a webapp framework built on google chrome, which is spyware). If you're on android, the app also renders in chrome (which is spyware), but that matters a bit less because android itself is a massive pile of spyware. iOS is also spyware that openly just copies all your files to a server in the US where they are "scanned for very bad things", retained indefinitely and may be accessed by your favourite state agencies without warrant.

Session is, fine, but the app can get really laggy at times of you are in it for a long period of time, pr especially if you scroll to an older message, this is my experience using it

Isn't Signal very similar to Telegram but focused on "security" and less features? Revolt is more like Discord. Matrix feels more similar to XMPP, and I see it as a compromise between Telegram style and Discord style. Matrix works well as a one to one chat as well as a team collaboration chat, but audio and video chats are very laggy. Self-hosted Jitsi would serve as an alternative to video and audio chats.