Scripts are not properly serialized in the Player when using Assembly Definitions

How to reproduce:
1. Open the “SerializationError“ project
2. Open the “SampleScene”
3. Switch the Player build to “Development Build” (File > Build Settings)
4. Build And Run
5. Observe the Player

Expected result: No errors are thrown and multiple “Spawner” GameObjects are instantiated
Actual result: The “A scripted object (probably ExampleMonobehaviour?) has a different serialization layout when loading. (Read 32 bytes but expected 48 bytes)” error is thrown and no GameObjects are instantiated

Reproduced with: 2021.3.36f1, 2022.3.22f1, 2023.2.17f1, 6000.0.0b13

Reproduced on: Windows 11
Not reproduced on: No other environment tested

Notes:
1. Not reproducible in the Editor
2. All errors logged in the Playe are provided in the internal comments
3. Could not reproduce in a new project
4. Not reproducible when removing the “Assets/TestAssembly/TestAssembly.asmdef” Asset