Thanks for getting back in this difficult times.
I've reached back their CC, but they said that this is how the new gen panels are supposed to look like. The best thing they can do it to get the whole display panel replaced (being in warranty), which I didn't want to. (In fact I don't have the Asus Splendid utility installed, that have notified to have caused similar issues in old laptops, it does not come with new ones)
I was wondering whether it has anything to do with any display adapter (tried updating it to latest, fresh install of win 10 etc.)?
I have seen some reports that indicate a similar phenomena (example: https://forums.intel.com/s/question/0D50P00004QxG3USAV/hd-620-yellow-screen-after-driver-update; I searched for "yellowish"). You can try playing with different driver versions if you wish. This linked report talked about the 7000 build, so you could try, for example, the 6519 release.