I'm getting this error if I try to change someone's username in Production as well as Sandboxes

Error: Please do not change usernames in the Trailhead Playground.

I am not in a Trailhead Playground so I don't know why this is happening

How do you change the username on a Trailhead or Developer Edition account? I tried updating the username from editing the user in Salesforce, but it is giving me a "Please do not change usernames in the Trailhead Playground" error. The same username is also being used on the Production org and it is giving me a Duplicate Username error for that user on Production.

We have two usernames in Trailhead that we want to use in our Salesforce production instance. These are not the main username of the org. When we try to change them we get the error -"Please do not change usernames in the Trailhead Playground." Salesforce support said they were unable to help. Is there anything else we can do?