If you really want an alternative, use matrix.org. It’s free open source software, end to end encrypted and server plus client side decentral. Especially the last thing is important, because if they start to enshittificate the client, just use another one without loosing contacts. If you do not agree with their server-service anymore, host your own or move to another community-server which is still in the same network, so you also don’t loose contacts. This way you avoid the most common reasons to leave a plattform with all the contacts.
Matrix has everything you have on Discord. On official servers you are currently able to send files up to 100MB. You can chat, call, stream, use it on every plattform native installed or on browser. The downside is, that some features are less polished, but I don’t think there is a better full-featured alternative. This will improve over time (donation can accelerate development).