This is the reply I got for the very same thing.
Thank you for giving the updated Community a chance!
Unfortunately, the new platform does not support (.) in usernames which is why you see the (_) in yours. However, in the updated community you now have the option to update your username as you see fit in your profile! All other users were also migrated so you can still connect with your fellow RV.net Alumni!
Let us know if there is anything else we can assist you with during this migration.
-Team Good Sam
Good to go since 1966