Keep in mind that I don't encourage anyone to use Discord, and you are definitely better off using open source alternatives like Revolt or Matrix.
However, if you absolutely need to use Discord (which I will not advocate), the least you could do is either use it in private browsing and erase the cookies after use, or use any open source client listed in this post!
Today i'll be showing you some open source clients to Discord that will at least try to give you some privacy instead of the original Discord client. Before you use any of these, make sure to turn off Discord telemetry in settings, then uninstall Discord and replace it with these open source clients, or as I said before you can use it in private browsing and erase the cookies after use!
Goofcord (Probably the best option!)
This client has such a silly name, but let me explain what it is first lol. Goofcord is a Discord client that focuses on privacy and customization while providing you full control over everything. It blocks most tracking and uses a variety of features, such as message encryption, to improve your privacy and security. It also includes Vencord and Shelter built in, uses Invidious links instead of YouTube, performs much faster than the original Discord client, has great support on Linux, Windows, Mac and even Windows 7/8 systems and is the best client on this list. I highly recommend it! Download it here on the GitHub
Webcord is a Discord client built without the Discord API. It significantly improves the user's privacy. It prevents known tracking and fingerprinting methods, but it does not end there. It also maintains permissions to sensitive APIs such as the camera and microphone, and it creates its own user agent to match the one used by Chromium browsers. Webcord is also fully written in Typescript rather than Java, runs on Electron, and is very customizable. Download it here on the GitHub
Datcord is an open-source Discord client that respects your privacy, uses Firefox instead of Chromium, and renders emojis better than the standard Discord client. Keep in mind that it just removes some of the tracking, and Discord may can still track you (Just not as much). It will still feel the same as the original Discord client, just significantly faster, and if your computer can't run Goofcord or Webcord, this is a viable alternative! Download it here on the GitHub
Spacebar is a free, open-source communication platform that is compatible with Discord. It is decentralized, adjustable, expandable, secure, and highly customizable. You can easily add your Discord bots and other content to it, and this is likely the best solution for people who prefer to selfhost. I would not call this an open source discord client, but rather a discord compatible alternative.
There is actually no client used for Spacebar at all, you just simply make a account and use the website!
Mobile Support
Aliucord (Android)
Aliucord is a open source modification of the original Android discord app which blocks most Discord Tracking/Analytics (Not all of them), has support for Plugins and has a In-app updater system to keep Aliucord and your plugins up-to-date!
Unfortunately, there is no Open Source IOS Discord client available since IOS is proprietary (unless you jailbreak your phone, which is extremely risky) or until Apple makes IOS open source, which is highly unlikely going to happen in the future. You're probably better off using Discord on your PC only.
Will you now have 100% privacy with Discord? No, you won't, and as I previously stated, your best option is to use a Discord alternative such as Revolt or Matrix, but if you absolutely must use Discord (which I do not recommend), you can at least use one of these Open Source Discord Clients that will at least attempt to provide you with some privacy. Choose whatever runs on your computer best and stick with it!
As always if there is any incorrect information on this post, please notify me and I'll change it right away!