BAD APP ICONS
Typically on Huawei devices and special Android versions where themed icons are provided by the OS in such a way that is not compliant with Android standards icons may appear to be small.

WORKAROUND #1
Disable the option Use highest resolution icons:
►Höchste Icon-Auflösung verwenden
►Mayor resolución iconos
►Utiliser les icônes haute resolution
►Legmagasabb felbontású ikonok
►Maior resolução ícones
►Использовать значки высокого разрешения

WORKAROUND #2
Much better results can be achieved by using an icon pack.
Please watch this video on how: