The exam was retired on 6/30/2019 but will be recognized for competency until 6/30/2020. For PPM Certification, the exam is being replaced with https://www.microsoft.com/en-us/learning/m365-teamwork-administrator.aspx I don’t have the official Microsoft word on why, but if I had to guess/assume: (1) more of Project functionality is being incorporated into the web and hence the other exam, and (2) it’s all about Teams.
You are correct and sorry for the confusion. The Project test is retired and there is no replacement. That test was also one of the requirements for a PPM certification, which is where the Teams course is being added. It is not technically a replacement but more a removal and add. Hope that helps.