I don't use Discord anymore but the phone number thing seems new, in the past I was able to visit as a guest and be able to read messages but not chat. Then again Twitter and Reddit are doing the same thing now and forcing people to log in, so I'm not surprised.

Considering how many community groups and open source projects now use a Discord in place of a public forum this looks like a disaster going forwards since all the information in there will become locked up. And of course the chats and internal discussion threads aren't indexed by search engines.