It appears Deltarune isn’t the only indie game that’s been dropped from the eshop.
We are sorry to report that YUMENIKKI -DREAM DIARY- has temporarily been removed from the Switch eShop (NA & EU) due to a change in the rating. We ask for your patience while we resolve this issue.
— 【Official】YUMENIKKI –DREAM DIARY– (@Y_DREAMDIARY) March 5, 2019
Deltarune was also removed for ratings complications, although only for the NA eshop. Hopefully both these games get these issues sorted soon.