So experimenting with the PC version a bit, you can find out quickly that the size of Bokeh shapes is correlated with the internal resolution the game is running at.
So Digtal Foundry running at 960X540:
Switch running at ??????:
My PC running at 640X360:
So that makes me think that either the internal resolution of Bokeh Depth of field has been quartered or halfed or whatever, or the game is much lower resolution than 960X540 in undocked mode.