Refer to doc. https://docs.unity3d.com/jp/current/ScriptReference/Events.UnityEventBase.RemoveAllListeners.html
It says that RemoveAllListeners can only remove listeners attached at runtime.
Refer to doc. https://docs.unity3d.com/jp/current/ScriptReference/Events.UnityEventBase.RemoveAllListeners.html
It says that RemoveAllListeners can only remove listeners attached at runtime.