It's a weekly cycle due to reporting disruptions over the weekend.
Use a 7-day moving average to get a better picture. Holidays and such can still be disruptive but the 7-day average solves most of it.
According to Evaluation of the Effect of Density on Potato Yield and Tuber Size Distribution potato tuber size was estimated using a normal distribution but they are not normally distributed
They found that a Weibull distribution with specific parameters estimated better than a normal distribution.
In fact you should not expect a normal distribution because ...