There is a difference between revenue and cash flow. CF does not recognize all proceeds of a season pass in the quarter it was sold. The price of the pass is divided against the forecasted number of visits, to equal an approximate price-per-visit. Each time a season pass is scanned, a portion of the purchase-price is recognized as revenue.
If I use my pass in March, June, September and November, the money I spent on the pass will be reported as revenue spread across all 4 quarters.
Cedar Fair is essentially deferring season pass revenue from 2020 to 2021.