DownloadHandlerScript.CompleteContent is called twice when building for WebGL

Reproduction steps:
1. Open this site https://cors-anywhere.herokuapp.com/ in the browser
2. Click the "Request temporary access to the demo server" button (to enable CORS on that site and send web request)
3. Open the attached “IN-104851.zip" project
4. Open the “SampleScene”
5. Build and Run for WebGL (File > Build and Run)
6. Observe the Player in the browser

Expected result: “CompleteContent” log appears once
Actual result: “CompleteContent” log appears twice

Reproducible with: 2021.3.50f1, 2022.3.63f1, 6000.0.51f1, 6000.1.8f1, 6000.2.0b5, 6000.3.0a1

Reproducible on: Windows 10 (user reported), Windows 11
Not reproducible on: no other environment tested

Note:

• Does not reproduce in the Editor or Android and IOS builds