My apologies.
The UI analogy was not appropriate.
What I fear is that slots may or may not display on a whim.
For example, I would write the following code to refer to a prefab named Test to which I have a Test class attached.
@property(Test)
public test: Test = null!
This looks perfectly fine, as there is no error.
However, it cannot be used because the slot is not displayed.
If you change the code to the following, the slot will be displayed.
@property(Prefab)
public test: Prefab = null!
However, this does not tell us the identity of test, so we must do getComponent to use the functionality of the Test class, and there is no guarantee that the test class is attached to this prefab.
Also, the use of getComponent causes me the following problem
Yes, in Unity the following process shows the slot without any problem.
@property(Test)
public test: Test = null!
However, there is no explanation for this issue on the difference with unity page.