Where I am from, I know of people that would role their eyes at me if I filmed with a phone, even if it is 4k. My DP who has a 4k phone and he doesn’t use it for anything else but filming. I tend to think, there are a bunch of camcorders that boast 4k on amazon, why not use one of them if you are going to shill money for something that is 4k? My experience with a phone is some things are harder. Getting the right exposure. Keeping people in focus.
And some DP’s can tell you when something was filmed on an Iphone. They can tell the difference. I have a hard enough time getting people to take me seriously. And some of the filmmaker groups on facebook, I would just about get laughed out of the group.
I also have a fairly important guy coming from California to be an extra. I don’t think he would be impressed if I was shooting the episode he is in on an Iphone.