You probably have heard about security giant Kaspersky having previously fired some shots (figurative ones, which translated into a very real antitrust complaint recently) towards Microsoft. The gist of the issue stands on Windows' handling of third party security software suites, with Windows sometimes removing those suits' installations on basis of "incompatibility" with more recent Windows versions. Other points of conflict mention the coloring in Windows Defender, where a user's security status appears as "not green", which leads customers towards believing that even though their systems have a third party security software installed, only Windows Defender can really and fully protect them (which is visually conveyed by the Window adopting a green coloring when customers select to activate Windows Defender.)