YouTube API thumbnail urls not resolving - youtube

Question

I am hoping this is a one off, but today I came across a video that reports the following when calling the "Videos: list" endpoint by a videoId:
"thumbnails": {
"default": {
"url": "https://i.ytimg.com/vi/**uEGlS01**/default.jpg",
"width": 120,
"height": 90
},
"medium": {
"url": "https://i.ytimg.com/vi/**uEGlS01**/mqdefault.jpg",
"width": 320,
"height": 180
},
"high": {
"url": "https://i.ytimg.com/vi/**uEGlS01**/hqdefault.jpg",
"width": 480,
"height": 360
},
"standard": {
"url": "https://i.ytimg.com/vi/**uEGlS01**/sddefault.jpg",
"width": 640,
"height": 480
},
"maxres": {
"url": "https://i.ytimg.com/vi/**uEGlS01**/maxresdefault.jpg",
"width": 1280,
"height": 720
}
}
... but neither the "maxres" or "standard" urls render an image (they 404 and render the nasty YouTube default grey image). Usually when those sizes were not available, those objects were not in the array.
Can anyone shed some light on this?
EDIT **
I should mention that the remainder of the thumb urls work as expected and embedding of the video fails to render a poster image with the exception of Chrome on desktop (which uses WEBP)