If you want help, you need to give us the complete query you have sent, as well as the complete response you have received.

I have used sample API request from API reference:

import requests

url = "https://api.themoviedb.org/3/tv/196288?language=en-US"

headers = {
    "accept": "application/json",
    "Authorization": "KEY"
}

response = requests.get(url, headers=headers)

print(response.text)

But the issue appears to be resolved now. So either somebody really had just added the dates at the time when I first opened this issue, so the API database didn't yet update, or it didn't update for some other reason, but my setting the show type to Returning Series and then again to Ended triggered new database update. Anyway, everything is OK now, I'm closing this discussion.