Depth of field effects caused by long focal length lenses (preferred in portraiture for this reason), called "bokeh". In this case the light is coming into front lens elements, and it doesn't appear to be corrected for distortion, and then not uniformly focused onto the surface of the camera's sensor. Potentially this was for a Imax dome.

So, no, this doesn't have anything to do with smart phones.

In ye' olde times, induced background blur would have been a gaussian blur in software. I'm not sure what special magic they do today. https://arxiv.org/abs/2006.05698 suggests things have moved on.