The Pinball Arcade has been removed from the Nintendo eShop on Nintendo Switch. According to FarSight Studios, this was done as a result of a licensing issue. However, you can rest assured that the developer is working on putting the game back up. The official announcement from the development team is as follows:
Unfortunately, Pinball Arcade for Nintendo Switch had to be taken off the eShop today due to a licensing issue. We at FarSight sincerely apologize for any disappointment and inconvenience. Once we get the issue resolved, we will be putting the game back in the store.