In the New User Experience / Modern UX, the Phase Task List has a circle to indicate if a Task is Open or Completed. The Tool Tip shows 'Open' when it is open and 'Completed' when it is marked Completed. The Tool Tip should be the same as what is shown on the Task Board
This issue is caused by DE47928
Release: CODFSS99000-15.5-PPM SAAS FedRAMP-Sandbox-Small Environment
This issue is tentatively planned to be fixed in Clarity PPM 15.6.1.