If you mean the painting program window around it I would call it breaking the fourth wall. If you mean the drawing style in which the characters are drawn, I don’t know a single term for it but I guess we could describe some aspects of it. There is no line art so maybe “lineless”. There are not many values in terms of lighting so maybe “flat”. How the areas of colour are laid down reminds of painting, sometimes people call digital art that is done like a painting or looks like a painting “painterly”.