Issue statuses
What can you do?
You can customize the background color and the text color of the issue statutes.
Example :
How can you do that?
You need administrator privilege to customize the colors. Go to admin area > Issue statuses (direct link : redmine_url/issue_statuses)
Click on a status and change the Bg color & Text color fields (Here is an example of a color palette : https://tailwindcss.com/docs/customizing-colors)