YouTube Data API returns wrong size for "maxres" thumbnail image? -

with youtube data api, can retrieve list of thumbnail images video resource. request...

get https://www.googleapis.com/youtube/v3/videos?part=snippet&id=dum1284tqfc&fields=items%2fsnippet%2fthumbnails&key={your_api_key} 

...generates response...

{  "items": [   {    "snippet": {     "thumbnails": {      "default": {       "url": "https://i.ytimg.com/vi/dum1284tqfc/default.jpg",       "width": 120,       "height": 90      },      "medium": {       "url": "https://i.ytimg.com/vi/dum1284tqfc/mqdefault.jpg",       "width": 320,       "height": 180      },      "high": {       "url": "https://i.ytimg.com/vi/dum1284tqfc/hqdefault.jpg",       "width": 480,       "height": 360      },      "standard": {       "url": "https://i.ytimg.com/vi/dum1284tqfc/sddefault.jpg",       "width": 640,       "height": 480      },      "maxres": {       "url": "https://i.ytimg.com/vi/dum1284tqfc/maxresdefault.jpg",       "width": 1280,       "height": 720      }     }    }   }  ] } 

(api explorer)

the maxres object has width , height of 1280 , 720. however, url (https://i.ytimg.com/vi/dum1284tqfc/maxresdefault.jpg) points 1920x1080 image.

it seems "maxres" thumbnail generated same size original uploaded video, , size of particular video (https://youtu.be/dum1284tqfc) 1920x1080.

i cannot find 1280x720 thumbnail image video.

1. what width , height properties refer to?
2. how real width , height of thumbnail images youtube data api?
3. is there 1280x720 version of thumbnail image?

this appears bug in youtube's api. according documentation, maxres thumbnail corresponds to:

the highest resolution version of thumbnail image. image size available videos , other resources refer videos, playlist items or search results. image 1280px wide , 720px tall.