According to new ansers of the administration staff at the forum, they retract about the old official explanation in which they said that the yellow band at the bottom of the phone is a designed feature because of the light sources localization. It seems that now this explanation is no longer valid since they actually said that is a "psycological thing" https://forums.oneplus.net/threads/re-yellow-screen.40239/page-80#post-2512312