Hi Erel, thank you for your answer!
I remember reading here somewhere about how it would be better to have different icons with different sizes for different resolutions because the downscaling android does when is needed does not always looks nice.
I don't have any icon.png that's a green droid on any res folder. My project has the original icon, with which was working fine (4 different icons in ldpi, mdpi, etc); I've replaced the following lines in the manifest and added foreground.png and background.png in the mipmap folder.
'SetApplicationAttribute(android:icon, "@drawable/icon")
SetApplicationAttribute(android:icon, "@mipmap/ic_launcher")
Regards!