One flag received in the past was the discrepancy between Design Style Guide design decisions and in-production reality.
Example: treatment of font family recommendations, with platform specific fonts for sans-serif -apple-system, 'BlinkMacSystemFont', 'Segoe UI', … vs in one of our most prominent interfaces Vector/Desktop not following above with 'Helvetica Neue', 'Helvetica', 'Liberation Sans', 'Arial', sans-serif.
As designer, I'd like to be able to have a clearly identifiable way to see if a token is legacy or part of the current design system.
As developer I'd like to identify legacy values as well and possibly see if they are used in the right places and are able to be removed if not.
My idea for styles that are currently in production and should be reflected in design tokens/variables as (former) design decisions that are not in the Design Style Guide, but we haven't had time to align them to DSG due to external dependencies (like community liaisons outreach) would be to have --legacy variable signifiers.
(Open question) They could live in wikimedia-ui-base file or an additional file wikimedia-ui-base-legacy to be super clear, that is deprecated from the beginning.
So font-size-base--legacy: 0.875em as another example for desktop not being standard, but following a former design decision.
With that devs have a clear indicator of old design tokens and it's simple to search for them.