If you are using Confluence Data Center and your administrator has temporarily switched your instance to Data Center Read-only mode, you may notice changes to the behavior of ThemeBuilder. These behaviors are displayed only while your instance is in read-only mode.
Set Flag macro functionality is disabled
Set Flag Link macro functionality is disabled
Remember that you cannot edit or create Confluence pages in read-only mode.
See Atlassian’s Using Read-only Mode for Site Maintenance to learn more about general Confluence use in Data Center read-only mode.