What they mean by this headline:

• If you don’t access “unsafe” material (currently meaning NSFW channels, blurred images, DMs from non-friends) nothing is changing in how you use Discord. Though there are some rumours about a “smart filter” that further restricts content in channels.
• If you want to access any of the above, Discord first tries to “guesstimate” your age based on "data they already collect"
• If that doesn’t work/has too low of a confidence, they ask you to verify your age via selfie or ID. Thsy claim Discord doesn’t get access to your ID, only the age on it, but it is most likely still uploaded to the service that does the checking.

TLDR: the headline is crap, and the same verification already present in UK and Australia is being rolled out to everyone.