Windows Defender and other Microsoft products will begin to remove programs that display coercive behavior designed to pressure a user into purchasing their software. This includes registry cleaners and system optimizers that offer free scans, detect issues with alarming messages, and then require the user to purchase the product before fixing anything. Microsoft has updated their software evaluation criteria to include behaviors that will no longer be acceptable. Companies who develop these programs can submit their software to Microsoft for validation using the Windows Defender Security Intelligence portal. Microsoft will then evaluate the program and determine if the program will be detected and removed on March 1st.
Source: https://www.bleepingcomputer.com/news/microsoft/microsoft-drops-the-hammer-on-coercive-registry-cleaners-and-system-optimizers/