In the following issue on the Dracula Theme you can see multiple people being unable to search for the this theme or any dark theme for that matter, while “Adapt to system” is active.
Is this intended behavior? I assume that Obsidian detected the system as running light mode and thus initially only searches for light themes, but not even listing dark themes as being available, nor giving you the option of looking for them makes no sense to me.
Also the Dracula theme features both dark and light in the theme file (even though both look the same) so it should show up regardless.
In the community-plugins.json file, the Dracula Official theme is listed as only supporting dark mode, so the last sentence is incorrect.
The behavior is this way because if the app is set to “Adapt to system” then the theme would be broken when the OS changes between light/dark modes.
We might improve on this behaviour in the future.