An Idea will display a Red face when it is behind schedule as defined on the Idea Timelines and reflected on the Gating Plan.
This will be reflected in the Gating Plan, Idea Edit -> Gating Plan.
I.e. This particular Idea is behind schedule, with its implementation plan. This can be resolved by Changing the Original Target Date to a future Date or Capturing a Revised Target Date.
To ensure an Idea is within the schedule, please make sure that the relevant workflows are completed as defined on the Idea Timeline and subsequent actions are completed to avoid the Idea being penalized on the Pipeline.