Hello there[url=https://cdn.discordapp.com/attachments/902560216871239752/989591085506515074/Hellothere.gif],[/url]
If your Bungie Name has been changed to "Guardian####", that indicates that some part of the name broke the [url=https://www.bungie.net/7/en/Legal/CodeOfConduct]Code of Conduct[/url] or the [url=https://help.bungie.net/hc/en-us/articles/7648312251284-Bungie-Name-Guide]Bungie Name Policy[/url], was filtered, and [b]can no longer be used. You can try a different name if you have not previously changed it.[/b] If the system is not allowing more changes, there is no way to override it.
names that appear to be including personal info are prohibited under CoC/Name Policy, if you've been filtered to Guardian then Bungie have deemed your name as violating CoC/Name Policy and you cant use the same name again.