I have several friends who use Discord as their primary social outlet. The vague way this change is being rolled out is causing a lot of heartburn for them.
It's strange to have a social platform force everyone to change their screen names. The vague way that they're rolling out the change over "several months" without any indication of timelines is making it worse.
From a product point of view, it would ease the pain if they would have communicated each person's username selection date in the app. Instead, they gave vague advice to watch for some unspecified in-app notification to pop up at some time in the next few months. For people who are anxious about keeping their screen names, this is a recipe for anxiety.