4 pane comic of dolan on the left and spooderman on the right
pane 1 (dolan): cum join opensurce cummunity!
pane 2 (spooderman): shure! how joyn?
pane 3 (dolan): Here discord! (with discord logo)
pane 4 (spooderman with tears in eyes): y u do dis?
Using phone numbers as second factor authentication is neither secure, nor is it in good faith. Force the customer to use something more anonymous and secure - like Fido keys or even TOTPs. Sneaking in ways to force the customer to reveal their personal details, in the name of security is a sinister dark pattern.
Phone number is the weakest form of 2FA but it's still an improvement. I've never had to use my phone in Discord though, I don't how Discord would even verify someone's phone number as legitimate. But like I said I have a couple Discord accounts with different emails, probably on 30-40 servers, and have never run in to this. So if they're collecting personal details in this really granular and specific manner, it seems like they're not doing a very good job at it.