I'm gonna get flak for this but no, Discord does not sell any user data, no matter how many times people keep repeating it. Quoting a legendary redditor here:

Discord's privacy policy repeatedly states that they do not sell your personal information:

We don’t sell your personal information. Our business is based on subscriptions and paid products, not from selling your personal information to third parties.

We make money from paid subscriptions and the sale of digital (and sometimes physical) goods, not from selling your personal information to third parties.

We do not sell the personal data of our users or share personal data for targeted advertising purposes.

‍No sale or “share” of personal information: The CCPA sets forth certain obligations for businesses that sell or “share” personal information. We do not sell or share the personal information of our users as defined in the CCPA.

This is a legal document that they will get in trouble for if they were lying. They've already been fined hundreds of thousands of euros for GDPR violations but that curiously did not include a fine for "took people's personal information and then sold them without consent whilst explicitly saying they didn't do that"

Discord further has no third party advertisements which they can use to "sell" your data by allowing those advertisements to target you.