How many CSS Style Sheets the module will have when you create a new UI Flow with a new and exclusive for it? If you have one screen in that flow the others Style Sheets (main) for the other flow will be also loaded? like in this scenario above
The default module theme would be unloaded when you switch screens that come from a UI Flow having a different theme than module's default one.
In your case, when the user navigates to NewUIFlowScreen, you won't see the FEBootcampAppThemeWO loaded (unless it is the parent theme for NewThemeUIFlow).
Thanks @Ravi Punjwani for your reply I was check on Browser´s inspect and I got what you said.
best regards,
Oliver