According to the updated rules for digital purchases in the eShop, from now on, money for pre-orders will not be withdrawn immediately, but seven days before the release. Thus, up to this point, the pre-order can now be canceled.
The change did not take effect until September 1, so all pre-orders made before August 31, inclusive, cannot be canceled.
Earlier in January, Nintendo won a lawsuit against the authorities in several European countries. Then the impossibility to cancel the pre-order and return the money in the eShop was recognized as legal. The new rules imply that although you can cancel a pre-order, after the withdrawal of funds, this opportunity disappears.