[quote] but I use my real first name [/quote] That is a violation of the Bungie Name policy. See the quote below taken directly from the Bungie Name guide. It is also a safety and security risk to use personal information in your online username. [quote]Banned Name Policies Any Bungie Name that violates these policies or our Code of Conduct will be changed to "Guardian[Random Number]" and players may face an in-game ban. Changes performed by Bungie may consume a player's unused name change. Policies include, but aren't limited to: [..] Personal identifying information (i.e. first and last names, email addresses, phone numbers, etc.) Full article at https://help.bungie.net/hc/en-us/articles/7648312251284-Bungie-Name-Guide[/quote] [quote] I haven't used a name change, but I can't even change my name back to what it was before.[/quote] Of course not, the name has been banned. If you still have a name change available, you can use it to change your Bungie Name to something else. Make sure whatever you change it to does not violate Bungie's policies otherwise, it will be changed again.

[quote]Banned Name Policies Any Bungie Name that violates these policies or our Code of Conduct will be changed to "Guardian[Random Number]" and players may face an in-game ban. Changes performed by Bungie may consume a player's unused name change. Policies include, but aren't limited to: [b]Personal identifying information (i.e. first and last names, email addresses, phone numbers, etc.)[/b][/quote] Personal info isn't allowed so thats likely why you were hit by the filter. you'll need to pick another if it wont let you use the old name.