Now, this could of course be a coincidence, but the spikes have been there every year since 2009 and I think eight years definitely establish a trend.
Why is this? Redditor it-will-last-longer suggests that
Bokeh is probably most apparent when you’re taking a night picture with Christmas lights in the background. People want to take fancy pictures during the holidays and want to find out how.
He also notes that “the term ‘dslr’ or ‘digital SLR’ correlates well with ‘bokeh’ and has similar peaks in December“, but that may also be related to purchasing decision on the holidays season.
I would not be surprised if this is indeed the case. Between Christmas tree lights, house decorations, Hanukkah Menorahs, and new years fireworks, there are definitely a lot of lights that would look fab out of focus. Of course this makes one wonder if sales of the Nifty Fifty and Bokeh Masters Kit spike in corellation.