The docs for app.json say this about the `notification.icon:
Local path or remote url to an image to use as the icon for push notifications. 48x48 png grayscale with transparency. Source
However I noticed by testing with sdk 25 on an Android 8 Pixel Device and Android 6 simulator, the status bar icon for push notifications and local notifications is way too small. Also, when I pulled down the screen to see the notifications, the same icon appears next to my apps’s name on Android 8, and it was the correct size. It was only the wrong size in the status bar.
I solved this problem by scaling my notification icon from 48x48 to 96x96. Now everything works fine for android. Do the docs need to be updated / is something else happening here? Also, maybe there should be a note that this notification icon is only for android - it doesn’t appear to make any different on ios.