Does chess change your username if you’re banned?


Hmm. Well your friend is mistaken. You didn't say if it was a fair play or an abuse closure but they had a reason. Your friend may not want to tell you but they had a reason.
Chess.com won't tell you why. There is no point in you asking. They only discuss account closures with the people directly involved.
And they don't let you keep the same name if you are banned but I've never heard that they make you take bizarre names.


That means the account was requested to be deleted. When that happens all identifiable information is removed from the account, including the username.
It's likely your friend's parents requested that.