The look and feel customization seems to have been disabled on the Cloud version of Confluence.
What are the options for customizing the current theme? And/or When will the feature be available again?
The ability to theme Confluence Cloud is heavily limited at the moment. You might find that any documentation related to theming APIs is completely out of date and doesn't work anymore. There's a discussion about this over on the Developer Community which I highly recommend reading. Particularly this response by Atlassian.
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