Can find the custom attribute on the return parameter of the delegate fine in Editor, but not in IL2CPP builds (tested Windows x64). Looking at the stripped C# assemblies, it appears that the attribute was not stripped out.

*Steps to reproduce:*

1. Build attached reproduction project with IL2CPP backend

2. Run the built application

3. Check "player.log"

*Actual results:* 

{{Remote return type: __ret}}

*Expected results:* 

{{Remote return type: InputPromptResponse}}

*Reproducible with versions:* 

6000.0.0b15
2023.3.0b10
2023.2.18f1
2022.3.15f1
2021.3.37f1

*Tested on (OS):* 

Windows 10