Why do pending actions in an action plan display differently

Summary:

I have noticed that sometimes an action in an action plan is displayed as text and sometimes it is in a green block and sometimes both are displayed. This occurs for required and optional tasks, with varying due dates. I can see that the green block is showing the 'next action'

Can someone please explain what the behaviour is.

Is it perhaps a task that is due in one or two days time?

Thanks

Version (include the version you are using, if applicable):

24C Next Gen

Code Snippet (add any code snippets that support your topic, if applicable):