Because Defender’s real-time protection identifies it as potentially unwanted software (PUA). You can create an exclusion, but only do so if you trust the source.
When this file is missing, corrupt, or blocked, you might see: Gsrld.dll Download
: The file performs checks to ensure the player is using a legitimate copy of the game. Functionality leading to crashes or instability.
Even if the file is clean, it might be for a different crack or game version, leading to crashes or instability. Gsrld.dll Download