My understanding is that this is due to aliases being embedded in the creation of the view. If you were to reference the same table, but bring it in as a custom SQL query then all of your fields would have the underscore. The table aliases were created when the view was created, so Tableau automatically grabs those aliases on import. If you didn't alias the new fields you created for the view, then they should still have the underscores.
Thank you Wesley!
Thanks, that makes more sense now from your explanation
So going forward it looks like if I add any new columns to the view, it will by default have underscore in it because the table aliases for the new fields were not initially their when the view was created, so I would have to update those fields to not include the underscores