No flash.
I don't know about what others may or may not find objectionable, I just know that the skin tones are not natural looking. I think we all know that most people find photos that are slightly more saturated and contrasty than reality to be more pleasing than photos that have accurate colors. I'm ok with that, but I like skin to look natural, not shifted orange or yellow.
When I use one of my Nikon, Pentax or Sony cameras, I always shoot raw and almost always do some processing. If one shoots jpeg SOOC with Nikon, Pentax and Sony and uses default settings, the jpeg files look a little too "cooked" for my taste. But all of those camera makers have a "neutral" or "natural" setting where at least the skin tones look pretty accurate and pleasing.
Clearly, the latest versions of the iPhone have more saturation and more of a yellow/orange cast than reality. It would be nice it there was a natural or neutral preset in the iPhone to bring the skin tones back down, but all of the presets are either more saturated, have more of a color shift or then go to B&W.
Here are a couple more examples of unprocessed iPhone photos where I find the skin tones to be objectionable.