Iphone 6s plus yellow tint

Hello YI9890!

I have never seen this issue before but I do not think your phone is broken. There is a feature on the iPhone called nightshift mode. It is to help from getting eye strain at night. In your settings click display & brightness then night shift. You can put it on a schedule or from sunset to sunrise. You could also just turn it on or off from your control center. I hoped this answered your question. Have a nice day

Go into Settings->Display&Brightness and check your Night Shift settings.

And check if your Night Shift is ON in Control Center.

This sounds like you might have "night shift" turned on.

You can check either in the control centre or in Settings/Display & Brightness. If it is turned on then you can set the colour temperature of the screen (i.e. make it warmer / less blue).

Update your phone.