The first Cursed book was released in late 2019 and the first season premiered not long after that in July of 2020, so it could be another instance where they plan to release the book not long before the second season.
However, since there is nothing confirmed and this is just a hint, all we can do is theorize for now.
With The Kissing Booth series, the author of the novels released books right around the same time that the movies were released on the popular streaming site, so Season 2 of Cursed could be moving in that direction.