Only Pearl Abyss-devs can answer when they submitted it (there's no publically visible review queue for iOS of course). But if PA only submitted it this morning (considering the full control you've got on PC and the far less stringent procedures on Android, that wouldn't even surprise me that such a mistake were to be made - public Apple policy only explicitely states launch review, not update review policies. It's easy to think that after that it works like Android, which would be an large error in thought), than expect the app back online anywhere between now and Thursday 9 AM (GMT+1).

 

So, yeah.... We'll just have to wait and see.

 

Tl;dr: there's a chance they forgot to calculate in the fact a review needs to be done every time and sent in in advance before you want to deploy. Any PA-devs reading this, please keep this in mind in advance and learn from your mistakes.

Unfortunately it sounds like they submitted it when they started patching, in which case we are all screwed.

If that was not the case they need to explain it to all of us so we know they did submit it in advance but they is a problem on apples end.

I have to assume the worst based on what they have told us.

This is not Apple's mistake. This is on PA. PA knows Apple's policies and prcedures. They have to if they want to post in the App store. This was a immense mistake by PA and an even bigger one by letting Android users play. 

Just as you’ve said, If they waited last minute then it will take a couple of days. Starting from PC to a mobile is already difficult enough and it adds a lot to their plate. Of course it’s something that can easily be missed since it’s.. well.. it’s Apple. Either way I got time, since I’m just a casual player in any game. everything will get itself sorted out and I hope they don’t stress themselves too much. This game is better then almost everything in Apple store.

That might be the case, but does anyone know what the patch consisted of?

I believe it was a holiday transition they were also adding a snowman pet if u go to the official page under the 3lines tab in news you will find a maintenance announcement for this patch

Here is the thing, they went through this with mobile launch, so either they are aware and dgaf or their memories are incredibly poor. Either way. Lolz.

From the official public Apple help doc for developers:
—-
Release the app yourself: Select “Manually release this version.” (Later, manually release the version.)

Automatically release the app after approval: Select “Automatically release this version.”

Automatic release the app but no earlier than a specified date: Select “Automatically release this version after App Review, no earlier than” and below this option, enter a date using the controls.