API [GET] Layout has strange values

I have two questions about the image below.

What does this {“1”: 61} mean?
If it is compatible with subPlaylstOption, it seems to be [58, 61].

*Actually, this playlist ID = 58 has already been unassigned.
(After that, I could publish it without any problem.)
Why is it left?

I apologize if the problem has already been fixed in the new version.