the icons appear to be fine for me in Develop, but i did modify the icons to suit my own tastes. But i'm not sure why that would be the case.
you can try what i made, but i run 1440 on ultra wide at 150 scaling, so maybe these are still still small on 4k.
https://drive.google.com/file/d/1BztpHQoY-zDCZccRLE_zJ370G9kwl-fX/view?usp=sharing