Package Manager doesn't show packages under the "Custom" tab when the packages are referenced locally

Reproduction steps:
1. Open the attached project “PackagesIssue”
2. Open Window → Package Manager

Expected result: The local packages are put under the “Custom” tab
Actual result: There is no “Custom” tab in the Package Manager window

Reproducible with: 2021.2.0a13, 2021.3.14f1, 2022.1.23f1, 2022.2.0f1, 2023.1.0a20
Not reproducible with: 2020.3.42f1, 2021.2.0a12

Reproducible on: macOS 13.0