Previously suggested more than 10 years ago, here https://www.outsystems.com/ideas/123/different-service-center-colors-for-different-environments/

Was marked as "Implemented" however the implementation was just adding a text label, rather than more prominent coloring or theme. Moreover, the "improvement" seems to have been removed in OS11.

Now that the top-menu has a white background, it should be easier to implement different colored backgrounds for different environments, either as a text-box accepting a hex-color value, drop-down selection, or pre-configured colors, for instance:

This would provide more differentiation between different environments and help prevent configuration mistakes, e.g. configuring mistakes on production, or incorrectly deleting modules