Update - Our version of the app was approved after they managed to get data from Firebase, but we could see from our analytics that this happened after the reviewer moved off WiFi to using data, making it feel more likely this is caused by something on Apple's WiFi. We have not seen the issue for a single user outside of the reviewers. I reached out to Firebase, and they said they cannot recreate it so will not look into it. My plan for upcoming reviews is to ask the reviewer to not use their WiFi. If the issue continues, I'm going to move away from Firebase as we cannot have a tool that is causing this much of an issue. Changing will be a fairly big job, but will save time in the long term. I'll post any other updates here.

To add some more context to the original post about this issue to see if it lines up with’s experience: We’re using Firebase version 9 with SPM. This version is slightly outdated (current version is v10.x) but this is still surprising behaviour. It appears fine everywhere else. The App Store reviews are using iOS 16.3. We had a successful review with iOS 16.2, but this has always happened on 16.3. Many users in prod use iOS 16.3 without issue. We have identified this is happening for Firebase Cloud Storage, rather than for Remote Config. The error reported is “An unknown error occurred, please check the server response”. Some people have suggested it’s caused by storage access rules, however the rules are as expected. Additionally, a specific error is thrown for when the user does not have access. We are using Xcode 14.2. We have emailed firebase support, but we're not expecting to hear about for a few more days. We are considering setting up a new cloud storage system in case this continues/ happens again.

(Continue) After some more investigation today, it appears the issue is with Firebase Cloud Storage rather than with Remote Config. The error being reported is "An unknown error occurred, please check the server response". Some people have suggested it's an issue with the access rules, but these are set as expected. Additionally, a more descriptive error is given when access is not allowed, so we are confident this is not the issue.

To add some more context to this: We're using Firebase via SPM. We're currently using version 9. This is not the latest version, but we're still surprised to see this. The reviewers are using iOS 16.3. This has been used in prod by many users who have not seen this issue. The app previously went through a review on iOS 16.2, and we did not have any issues. We're using Xcode 14.2.