Is the artist singles id not supposed to correspond to the track id or is this a bug?

Ex:
Using 2w9zwq3AktTeYYMuhMjju8 , an artist id, as the required parameter for getting artist singles
If I go into data -> artist -> discography -> singles -> items -> 0 -> releases -> items -> 0 -> id , i’ll find that the id is 4kG9LIFl6dYNUSLjABjTbV , and the item is of type single

However, when I use the single id as the required parameter for get tracks, I am returned with null