I suspect this is an artifact, but happy to be proved wrong. Jupiter orbits the sun every 12 years, close to the sunspot 11 year cycle. It is possible that the examined records cover a stage of both cycles in which the elliptic orientation of Jupiter (ie points of perihelion and aphelion) mapped on to the sunspot cycle, so there were less sunspots when Jupiter was closer. Could the precession of the Jupiter perihelion contribute to such an artifact?

I found a comparable artifact by mapping the apparent position of Saturn against the lunar nodes. Both have a roughly similar period (29yrs vs 21yrs), and because Saturn's apparent retrograde speed is very close to the speed of movement of the lunar node, if you do a time series over fifty years or so you will see that some angles are much more common than others. I initially thought this was interesting in terms of earth cycles but it is just an artifact. I am not trying to open discussion here on this except to illustrate that Jupiter perihelion and sunspot peaks would naturally be aligned for a long time, distorting the statistical evidence.