First, please understand that there are hundreds of different launcher implementations in use across the ~10,000 Android device models and ~2 billion Android devices. How a launcher chooses to represent your activity is up to the developer of the launcher. For example, there is no requirement for the launcher to use any icon at all (e.g., a launcher optimized for screen readers and visually impaired users). A launcher that does use some sort of graphical element might use your icon or not, and if if it does use your icon, it might modify it (crop it to a shape, apply a color filter, cause it to spin, whatever).
Your screenshot appears to be of the Android emulator. In that case, temporarily, you can set your targetSdkVersion
to be 25 or lower, and that particular launcher will not attempt to adapt your launcher icon.
However, please bear in mind that you will not be able to ship your app on the Play Store with that low of a targetSdkVersion
starting in a few months. So, if the Play Store is your planned distribution channel, you will need to get used to Android's adaptive icon system and deal with the fact that the shape of your icon will be changed on most Android 8.0+ devices.