I have a similar issue. Instead of the new grass icon, or the old launcher icon as on Windows (which is the most official one looking at tineye), the launcher seems to package an icon that is less bright and is scaled wrong. In the image I provided, you can compare the packaged icon (Latest Release) with the correct one (b1.7.3).
The icon cache is not the issue because I've set the look of com.mojang.Minecraft.png to the new logo and KDE Plasma reads it just fine.
journaljemmy
I have a similar issue. Instead of the new grass icon, or the old launcher icon as on Windows (which is the most official one looking at tineye), the launcher seems to package an icon that is less bright and is scaled wrong. In the image I provided, you can compare the packaged icon (Latest Release) with the correct one (b1.7.3).
The icon cache is not the issue because I've set the look of com.mojang.Minecraft.png to the new logo and KDE Plasma reads it just fine.