This had better be a Hanlon's Razor situation, because the alternative is...
The Fire Emblem Heroes update that launched last night has brought a nasty surprise for the free-to-play playerbase.
Players with the in-app purchase functionality disabled on their devices - a function offered on iOS via the "Screen Time" system - are reporting that they are unable to access the summoning screen even to use orbs earned through gameplay. An error message 803-4211 appears, and the only option is to return to the title screen. This was originally discovered on the game's Reddit page, including a screenshot of the error message.
Nintendo World Report has requested comment from Nintendo on this issue and will update once we receive a response. Players affected are encouraged to send feedback through the game's support system (Settings -> Misc. -> Customer Support -> Send Feedback) as well.