@lovehydration more or less, the rising sun was Japan flag in WW2, everytime a mangaka uses it it triggers CN and KR
but is still normal for Japan to use it in public events or special occasions so they just have to accept it, is possible that when manga with it are published in the 2 countries the publisher edits it out, but in a fanmade scan is all on the will of the person doing it
some years ago there was some bad backlash from BIg Hero 6 protagonist room having it when they showed in Korea if I'm not wrong
and some JP anime that were animated by korean teams didn't draw the rising sun flag in someevents like students graduations that could have it, it was mostly noticed by the hall with all the students having poor decorations and empty walls.