Regardless of the Tableau dashboard URL, the Tableau integration component shows "Debug Render Mode: X" at the top of the widget. Below is a screenshot using the pre-filled default sample URL:
Looks like the documentation for the component is very sparse: Tableau | Retool Component Library
It looks like you were able to get in contact with the support team about this but just in case anyone else runs into a similar issue:
You should be able to get rid of the "Debug Render Mode" text by appending
&:jsdebug=n to the end of your Tableau URL as per this thread. The dev team will look into making this more streamlined and we can report back here if they do!