How to reproduce:
1. Open the attached “BoatAttack.zip” project
2. Open the "Prefab Bug Test" Scene
3. Inspect the object "PrefabLoaderTest"
4. Enable "Do It" in the inspector
5. Observe the console

Expected result: No errors are shown
Actual result: “Could not load Prefab contents at path” error message is thrown

AND YET: Unity can load, edit, and save the prefb without errors.  So is the prefab corrupted or not? 

Reproducible in: 2021.3.42f1, 2022.3.41f1, 6000.0.14f1

Reproducible on: Windows 11
Not reproducible on: No other environment tested

Note: The “Island Level” prefab has only one root GameObject, error shows that it has 3 root GameObjects.

Same is true for the MainMenuLevel prefab.