A simple Google search turns up results from years ago that are still valid today: https://old.reddit.com/r/discordapp/comments/ircyh1/locked_o...

> You'll be required to register a phone number to your Discord account in order to continue the use of it.

If it doesn't rain one day, that's not evidence there exists no rain

That's about the level of evidence that your specific user account offers to you about whether phone verification is a thing their anti-spam algorithms can trigger...