Newtonsoft Json doesn't correctly serialize classes inside the Packages folder when in UWP and WebGL Builds

How to reproduce:

1. Open the attached project "REMOVE-DATACONTRACT.zip"
2. Build the project for UWP

Expected results: "Dictionary Count: 3" is displayed
Actual results: "Dictionary Count: 0" is displayed

Reproducible with: 2020.3.45f1, 2023.1.0a26, 2023.1.0b4, 2023.2.0a2
Not reproducible with: 2021.3.18f1, 2022.2.7f1, 2023.1.0a25

Reproducible on: Windows 10