It’s a Trend
Trends arise through copying and while sometimes we even speak of a ‘movement’ (“A tendency or style in art with a specific common philosophy or goal, followed by a group of artists during a restricted period of time, or, at least, with the heyday of the movement defined within usually a number of years.”) there is the problem of over-exposure and loss of meaning which will rapidly make that trend ‘mainstream’ and thus untrendy.
Pic: Above: Poster Design by Bob Wilson