According to a representative on reddit:
(note: trust at your own will, /tech/ does not)
>Are they recording and keeping everything I poast forever?
Allegedly voice chat is only used for transmission, never otherwise stored.
Also:
>"Messages are stored on our servers in google cloud and are encrypted at rest".
I have assumed that means Google can do analytics on them, as they didn't clarify when asked whether they are encrypted before transfer.
Useful links (trigger warning!!!1! : reddit.com )
https://old.reddit.com/r/discordapp/comments/9bzaqd/i_requested_my_personal_data_package_discord/
>Staff 1: "I was super concerned by this post, because we do delete all content when you delete a message."
https://www.reddit.com/r/discordapp/comments/9plaz1/discord_privacy/
(non-staff replies)
>If you delete your messages, they will still exist on a cached version of their backups. It will take a certain amount of time in order for the cached versions to get replaced. No one but Discord would know that amount of time.
>If you deactivate, it will stay the same and your data is still there. The safest way is to delete everything you've ever sent and wait - say 3 months or so and then delete your account.
>Your messages won't be deleted if you delete your account. You would have to go through each message yourself and delete them, which, unless you only wrote a handful of messages, will be impossible without some API abuse (and probably getting the account disabled by discord anyways).