YouTube Data API search results include videos outside the specified channel - youtube-api

Question

I specified a certain channelId in the YouTube Data API query, but the results include videos from outside that channel:
https://www.googleapis.com/youtube/v3/search?part=snippet&channelId=UCVZyJ-yJ60EZyMXLnIs0_OA&maxResults=5&key={{your key}}
In the results there are items that are not from the channel specified by the parameter channelId in the request:
{
"kind": "youtube#searchListResponse",
"etag": "CqAEn3U3yOet5Dzo4akpnniRK58",
"nextPageToken": "CAUQAA",
"regionCode": "JP",
"pageInfo": {
"totalResults": 8,
"resultsPerPage": 5
},
"items": [
{
"kind": "youtube#searchResult",
"etag": "PzY2_uuWT5JXecEOIgv5a4H3RsE",
"id": {
"kind": "youtube#video",
"videoId": "820RgL1fc8g"
},
"snippet": {
"publishedAt": "2019-08-16T10:25:55Z",
"channelId": "UC9FTt8SigjBd2bzzH3QCCVQ",
"title": "薬師寺　新管主への継承法要",
"description": "2019/8/16.",
"thumbnails": {
"default": {
"url": "https://i.ytimg.com/vi/820RgL1fc8g/default.jpg",
"width": 120,
"height": 90
},
"medium": {
"url": "https://i.ytimg.com/vi/820RgL1fc8g/mqdefault.jpg",
"width": 320,
"height": 180
},
"high": {
"url": "https://i.ytimg.com/vi/820RgL1fc8g/hqdefault.jpg",
"width": 480,
"height": 360
}
},
"channelTitle": "奈良テレビチャンネル",
"liveBroadcastContent": "none",
"publishTime": "2019-08-16T10:25:55Z"
}
},
{
"kind": "youtube#searchResult",
"etag": "JIDp4JJTHmn1YL3QpbfG7ZkIhWg",
"id": {
"kind": "youtube#video",
"videoId": "qwmHF5kvfuk"
},
"snippet": {
"publishedAt": "2016-07-04T04:19:41Z",
"channelId": "UCHeX3CiVyozXzcYjLqmkXuQ",
"title": "落合西光寺双盤念仏～5分ver",
"description": "製作…平成27年度埼玉県民俗文化財を活かした地域活性化実行委員会30分verはこちら…https://youtu.be/QcJjlwqNRqk.",
"thumbnails": {
"default": {
"url": "https://i.ytimg.com/vi/qwmHF5kvfuk/default.jpg",
"width": 120,
"height": 90
},
"medium": {
"url": "https://i.ytimg.com/vi/qwmHF5kvfuk/mqdefault.jpg",
"width": 320,
"height": 180
},
"high": {
"url": "https://i.ytimg.com/vi/qwmHF5kvfuk/hqdefault.jpg",
"width": 480,
"height": 360
}
},
"channelTitle": "Hanno City",
"liveBroadcastContent": "none",
"publishTime": "2016-07-04T04:19:41Z"
}
},
{
"kind": "youtube#searchResult",
"etag": "WhRD0hdEdos_8_3sIMnSfKeBOos",
"id": {
"kind": "youtube#channel",
"channelId": "UCVZyJ-yJ60EZyMXLnIs0_OA"
},
"snippet": {
"publishedAt": "2019-03-15T07:18:32Z",
"channelId": "UCVZyJ-yJ60EZyMXLnIs0_OA",
"title": "世田谷デジタルミュージアム",
"description": "",
"thumbnails": {
"default": {
"url": "https://yt3.ggpht.com/ytc/AAUvwninEQgZmbCwRKlSlpaqXerK3i2pXTX2fw0ctyW5=s88-c-k-c0xffffffff-no-rj-mo"
},
"medium": {
"url": "https://yt3.ggpht.com/ytc/AAUvwninEQgZmbCwRKlSlpaqXerK3i2pXTX2fw0ctyW5=s240-c-k-c0xffffffff-no-rj-mo"
},
"high": {
"url": "https://yt3.ggpht.com/ytc/AAUvwninEQgZmbCwRKlSlpaqXerK3i2pXTX2fw0ctyW5=s800-c-k-c0xffffffff-no-rj-mo"
}
},
"channelTitle": "世田谷デジタルミュージアム",
"liveBroadcastContent": "none",
"publishTime": "2019-03-15T07:18:32Z"
}
},
{
"kind": "youtube#searchResult",
"etag": "mGoPgXXCpvtW28-eAzPkxjQ-goc",
"id": {
"kind": "youtube#video",
"videoId": "DgeWR7q2_V4"
},
"snippet": {
"publishedAt": "2014-08-22T05:32:22Z",
"channelId": "UC_kYlv-j7o3j1979t35htzQ",
"title": "双盤念仏(そうばんねんぶつ) 九品仏浄真寺 閻魔堂 平成26年",
"description": "東京都世田谷区にある九品仏浄真寺の閻魔堂で行われた双盤念仏(そうばんねんぶつ)です。 平成26年8月16日(土)撮影.",
"thumbnails": {
"default": {
"url": "https://i.ytimg.com/vi/DgeWR7q2_V4/default.jpg",
"width": 120,
"height": 90
},
"medium": {
"url": "https://i.ytimg.com/vi/DgeWR7q2_V4/mqdefault.jpg",
"width": 320,
"height": 180
},
"high": {
"url": "https://i.ytimg.com/vi/DgeWR7q2_V4/hqdefault.jpg",
"width": 480,
"height": 360
}
},
"channelTitle": "ヒコボン/ohiko2000",
"liveBroadcastContent": "none",
"publishTime": "2014-08-22T05:32:22Z"
}
},
{
"kind": "youtube#searchResult",
"etag": "f6Uukvz6P_iy8eqLdGrIckIzV6w",
"id": {
"kind": "youtube#video",
"videoId": "RPtB3ibF9Mg"
},
"snippet": {
"publishedAt": "2015-10-15T08:42:50Z",
"channelId": "UCH2rOy40BxSSfNZwcCuVGzg",
"title": "平成27年10月13日建長寺僧堂落慶法要",
"description": "",
"thumbnails": {
"default": {
"url": "https://i.ytimg.com/vi/RPtB3ibF9Mg/default.jpg",
"width": 120,
"height": 90
},
"medium": {
"url": "https://i.ytimg.com/vi/RPtB3ibF9Mg/mqdefault.jpg",
"width": 320,
"height": 180
},
"high": {
"url": "https://i.ytimg.com/vi/RPtB3ibF9Mg/hqdefault.jpg",
"width": 480,
"height": 360
}
},
"channelTitle": "建長寺",
"liveBroadcastContent": "none",
"publishTime": "2015-10-15T08:42:50Z"
}
}
]
}