Discord explicitly confirms in its privacy policy[1] that it collects the following information:

IP Address
Device UUID
User's e-mail address
All text messages
All images
All VOIP data (voice chat)
Open rates for e-mail sent by Discord

Discord does not explicitly confirm that it collects this information, but still collects it by default:

Logs of all of the other programs that are open on your computer

https://revolt.chat/ is an alternative