I solved it partially by enabling 'use app icons for notifications' . At first enabling this option did nothing, then realised you must manually restart the launcher for it to take effect. This option has its own negatives though.
Using Android style + 'use app icons' enabled, it fixes the mentioned issue, but before, some apps had their own special icon for notifications which are now replaced by the app one.
Using Android style + 'use app icons' disabled, there is a dark grey filter over certain apps notifications which looks bad and hard to tell what the icon actually is. (I'm starting to think this could be intentional by devs, to try make all notification icons a greyish color?) I don't think it looks good though, since the other grey icons which are supposed to be like that are very easy to understand, these modified ones just become almost a solid block of grey.
Using MIUI style fixes the dark grey filter over some notification icons but some notifications have no icons at all, just a big white square. Enabling 'use app icons' doesn't fix this
