if the user name doesn’t exist, IE you visit https://www.twitch.tv/myusername and get the “time machine page”, then the API will return
{"data":[]}
regardless of the method of deletion.
If a Username is "not active’ on the platfrom, then you get no data.
This includes but not limited to
- Account delete,
- Account TOS’ed,
- Account recycled,
- Account never existed in the first place.
There is no way to see if a given username is in the “recycle pool” or not