[REQUIRED] Step 1: Describe your environment

• Xcode version: 13.0
• Firebase SDK version: 8.7.0
• Installation method: CocoaPods
• Firebase Component: Auth/Core

(Added by me):

• iOS Version: 15.0

[REQUIRED] Step 2: Describe the problem

After about 30 min., users are being signed out by Firebase automatically. This behavior did not occur prior to iOS 15. My company has in place, multiple safeguards via the iOS SDK & Cloud Functions for Auth. This issue is only occurring as of iOS 15.0.

Steps to reproduce:

Tested on both phone auth & Sign in with Apple:

Test 1:
Sign in --> Terminate application -> Open app after 5 minutes --> still logged in.

Test 2:
Sign in --> Terminate application -> Open app after 25 minutes --> still logged in.

Test 3:
Sign in -> Terminate application --> Open app after 31 minutes --> logged out of firebase.

What happened? How can we make the problem occur?

This just started happening as of iOS 15 & Xcode 13.
We have tests in place in our development environment to ensure things like this are not our fault.
And, our application in the store is not experiencing this behavior.

Relevant Code:

N/A.