I'm proposing this topic (and volunteering myself as the author) because patterns similar to the one below are quite common in web design. I believe the formatting API is often overlooked, and developers who are unfamiliar with it might struggle to implement such designs.

The initial plan for the article:

• an overview of available formats with examples of how they can be used (e.g., adding an inline image to the citation in the Quote Block)
• how to unregister default formats
• how to add a basic format, similar to the one shown in the screenshot
• how to implement more complex format controls, such as the one in the Language Format, where a click opens a popover with multiple options.