@IvanPayne you can use solution as
@Leo Knight described — update icons file from standard ROM.
Or if you don't want to download and unpack standard ROM, you can do thing that I have described — update existing icons file. I can share with you icon_pattern.png file.
The problem of these two approaches that all changes will disappear after OTA. I'm currently trying to check third approach — put custom icons to
miui_mod_icons folder. So far working great. I hope it won't get overwritten after OTA, since these files does not exist in the ROM.
I'm using following approach — download APK file, then locate the main icon there, correct background there, and then save under correct name to
miui_mod_icons folder and reapply theme. Icons get updated.
You can do it yourself, or if it's not that many icons, I can help you. I'm not a fancy artist, but it's not the rocket science either. Updating icons to keep consistent look does not require much of the talent.
I have contacted
@ingbrzy to include my custom icons to the ROM. Maybe you can also ping him to show that problem indeed exists and we should not ignore it. Let me emphasize again: standard ROM has a white background for all non-standard icons. Which is definitely far better choice than the dark one.
Here is how the result of my approach looks like:
before:
after:
