What name are you trying to use?
Regarding the issue the latest update we have for the issue is they're still looking into it. You can try variants of the name you've chosen but there is a good chance they'll be being stopped by the filter as well.
[quote]We're currently investigating an issue where players are unable to change their Bungie Name. We will provide updates when available.[/quote]
https://x.com/BungieHelp/status/1843706081119293941