I wouldn't call this part of the situation a bug. I'm sure everyone has their own opinion about which is the "right" way to handle a mismatch of OS level preference and browser level theme though.

The underlying problem is Chrome exposes no (normal) setting to override the OS level setting at all, not necessarily that the preference shall always follow the browser's theme specifically.

This issue is related to appearance setting inside Chrome itself (which sets Chrome's appearance, not how it should work with websites AFAIK). The core feature of prefers-color-scheme (following the OS-level setting) is working as intended.

So I guess it hasn’t been supported anywhere in a sense.

Safari and Firefox are pretty small.