How to fix creating a new user on iOS every time app is uninstalled and installed again

Hello,

We are making a game in Unity, and for login we are using PlayFabSettings.DeviceUniqueIdentifier (which redirects to SystemInfo.deviceUniqueIdentifier for iOS).

Everything is perfect on Android. A player can uninstall the app, install it again, and they will login with the same user they were using before.

But on iOS, every time the app is uninstalled and installed again, it creates a new user. I vividly remember that this was not the case at some point, we were able to always use the same Playfab users on our test devices.

Here is the piece of code that could be relavant. If someone wants more info just let me know:

var deviceId = PlayFabSettings.DeviceUniqueIdentifier;
switch (Application.platform)
{
    case RuntimePlatform.IPhonePlayer:
    {
        var request = new LoginWithIOSDeviceIDRequest { CreateAccount = true, TitleId = _titleId, DeviceId = deviceId };
        PlayFabClientAPI.LoginWithIOSDeviceID(request, OnLoginSuccess, OnLoginFailure);
        break;
    }
    case RuntimePlatform.Android:
    {
        var request = new LoginWithAndroidDeviceIDRequest { CreateAccount = true, TitleId = _titleId, AndroidDeviceId = deviceId };
        PlayFabClientAPI.LoginWithAndroidDeviceID(request, OnLoginSuccess, OnLoginFailure);
        break;
    }
    default:
    {
        var request = new LoginWithCustomIDRequest { CreateAccount = true, TitleId = _titleId, CustomId = deviceId };
        PlayFabClientAPI.LoginWithCustomID(request, OnLoginSuccess, OnLoginFailure);
        break;
    }
}

Are we doing anything wrong? How can we fix this?

The issue resembles this: https://community.playfab.com/questions/15006/player-account-changes-on-ios.html

But in this one it states that as long as there are apps installed from the same developer on this phone it should keep the same device ID. In our case, we have our other app from the same dev account installed on this phone, yet, uninstalling still makes it impossible to get the same account on Login.