Youtube api shorts thumbnail in portait format

I am using youtube api V3 to retrieve video thumbnails.

For example video: https://www.youtube.com/shorts/OGimWaDYMbs

API will return:

https://i.ytimg.com/vi/OGimWaDYMbs/maxresdefault.jpg

However thumbnails are in 16/9 format

If I explore their html, I can see they use this (which is exactly what I want):

https://i.ytimg.com/vi/OGimWaDYMbs/frame0.jpg

Is this documented somewhere? I dont want my code to fail.