How to reproduce:
1. Open up a new 3D Project
2. Navigate to Project Settings > Services and log in to Services and Create project ID
3. Navigate to In-App Purchasing and select "No" when prompted on age requirements
4. Rapidly click different areas in Project Settings

Expected result: No errors are thrown
Actual result: ArgumentNullException is thrown in Console

Reproducible with: 4.5.1 (2020.3.42f1, 2021.3.15f1)
Couldn't reproduce with: 2022.1.24f1, 2022.2.0b16, 2023.1.0a19 (Project Settings act different)

Error message:
2021.3: "ArgumentNullException: Value cannot be null.
Parameter name: e"
2020.3: "NullReferenceException: Object reference not set to an instance of an object
UnityEngine.UIElements.StyleSheets.HierarchyTraversal.Recurse"