@ddbeck When you get a moment would be great if this could be sanity checked.

I don't think either of these notes belong in BCD. I think it's a given that there will be lots of ways for a user to select their preferred color scheme and Firefox providing these particular methods is not a compatibility distinction worth mentioning. Moreover, I think these notes suggest that Firefox is doing something non-conforming, when it's not. From the spec:

The method by which the user expresses their preference can vary. It might be a system-wide setting exposed by the Operating System, or a setting controlled by the User Agent.

If the contents of these notes are genuinely useful to web developers, then I think the page content needs to address that in a more direct why, providing some context for relaying this information. Stuffing them into a note box on the page doesn't get at why we're telling web developers about this, but neither does stuffing the same notes into the compat table. For instance, maybe these settings are useful tools for testing different color schemes; I'd much rather learn about that in the context of a section (or page) about testing prefers-color-scheme.

@ddbeck Thanks for your detailed answer.