YouTube API Returns Wrong SubscriberCount - youtube-api

Question

I have two channels examples:
https://www.youtube.com/channel/UC56eaiucsjSfKgevcaGcn2w => real sub 150k
https://www.youtube.com/channel/UC-2Zibu3OGJdIisYaODXhbQ => real sub 208k
This is what was returned from the Channels list endpoint:
{
"kind": "youtube#channelListResponse",
"etag": "wVkhi3RvF1ayB9ou0W6KZcanGZE",
"pageInfo": {
"totalResults": 2,
"resultsPerPage": 5
},
"items": [
{
"kind": "youtube#channel",
"etag": "QI30osPYB_sy-uwNipgDhEPKRso",
"id": "UC56eaiucsjSfKgevcaGcn2w",
"statistics": {
"viewCount": "17359612",
"subscriberCount": "320",
"hiddenSubscriberCount": false,
"videoCount": "26"
}
},
{
"kind": "youtube#channel",
"etag": "IjATUKKNgPUxmtHQWicg_r22hqc",
"id": "UC-2Zibu3OGJdIisYaODXhbQ",
"statistics": {
"viewCount": "1723670",
"subscriberCount": "18",
"hiddenSubscriberCount": false,
"videoCount": "1"
}
}
]
}
When you go to the links above, and navigate through the channel, I noticed that the channel Id changes and the API returns the correct sub count for the new Id.
I am unsure how a unique video Id can be linked to more than one channel, What kind of channels are these? merged, linked, or something else? and how does the user do this?

Answer 1

"click on the same link you gave me, then click on the first video" there isn't any video on my side. Using PlaylistItems: list with the channel uploads playlist I get 26 videos and the first one is hVyJsXCXyuo. Even if all retrieved videos are unavailable, for the first video I indeed see that the channel real subscribers count is 150k and if I click on the channel name I get redirected to another channel that is UC4LyPYXnF07KF97Nb8vE_Pg which indeed has 150k subscribers.
Then you can use Channels: list to get the correct subscriber count using id=UC4LyPYXnF07KF97Nb8vE_Pg cf https://www.googleapis.com/youtube/v3/channels?part=statistics&id=UC4LyPYXnF07KF97Nb8vE_Pg&key=YOUR_API_KEY
Note that under a video the channel id you are redirected to seems to differ if you click on the channel avatar or the channel name on a desktop. The following redirection are done if you are on a phone or a computer and if you click on the channel avatar or channel name:
Phone:
Name: UC56eaiucsjSfKgevcaGcn2w
Avatar: UC56eaiucsjSfKgevcaGcn2w
Computer:
Name: UC4LyPYXnF07KF97Nb8vE_Pg
Avatar: UC56eaiucsjSfKgevcaGcn2w