As of right now, version 205.15 of Discord has the old UI and it works for me. You can get an APK for it. That version comes with a bigger font but it can be disabled by going into the Appearance settings. Disable auto updates for your apps.

https://www.apkmirror.com/apk/discord-inc/discord-chat-for-gamers/discord-chat-for-gamers-205-15-stable-release/discord-talk-chat-hang-out-205-15-stable-android-apk-download/download/?key=96e169a403f0a1d76e9b173f9c462e397c3e24f5&forcebaseapk=true

Good luck!