getHashtag method fails with 400 status for certain Cyrillic hashtags

[axercode]

Steps to reproduce

Description

When using the getHashtag method with certain Cyrillic (non-ASCII) characters, the request fails with a 400 status code. The issue appears to be related to the encoding process in the getHashtag method, specifically in the parameter encoding step:

const params = encodeURIComponent(u8ToBase64(writer.finish()));

Reproduction Steps

1. Initialize Innertube client
2. Try to fetch hashtag data using getHashtag with Cyrillic characters

const response = await youtubei.getHashtag('биткоин');

Debug Information

I've noticed different encoding results for working vs non-working hashtags:

Working hashtag (#биток):

[getHashtag] Encoding hashtag: биток
[getHashtag] Params: 6gUOCgrQsdC40YLQvtC6GAE%3D

Failing hashtag (#биткоин):

[getHashtag] Encoding hashtag: биткоин
[getHashtag] Params: 6gUSCg7QsdC40YLQutC%2B0LjQvRg

The encoded parameters have different structures for working and non-working cases. The encoding process (u8ToBase64 followed by encodeURIComponent) seems to handle some Cyrillic strings correctly while failing with others.

Test Cases

Working hashtags:

• биток, мир (Cyrillic word)
• crypto (Latin characters)

Failing hashtags:

• биткоин, море (Cyrillic word)
• Other Cyrillic hashtags

Environment

• YouTube.js version: 12.2.0
• Node.js version: 23
• Operating System: Linux

Additional Context

• The same hashtags work correctly on YouTube's web interface
• The issue seems to be related to the encoding process in the getHashtag method
• This issue is specific to the getHashtag endpoint
• The difference in encoded parameters between working and non-working cases suggests a potential issue with the encoding pipeline for certain Cyrillic strings

Failure Logs

InnertubeError: Request to https://www.youtube.com/youtubei/v1/browse?prettyPrint=false&alt=json failed with status 400
info: '{\n' +
    '  "error": {\n' +
    '    "code": 400,\n' +
    '    "message": "Request contains an invalid argument.",\n' +
    '    "errors": [\n' +
    '      {\n' +
    '        "message": "Request contains an invalid argument.",\n' +
    '        "domain": "global",\n' +
    '        "reason": "badRequest"\n' +
    '      }\n' +
    '    ],\n' +
    '    "status": "INVALID_ARGUMENT"\n' +
    '  }\n' +
    '}\n',
  date: 2025-02-12T08:02:09.288Z,
  version: '12.2.0'
}

Expected behavior

• Should return hashtag data similar to what's returned for Latin character hashtags
• Should work similarly to YouTube's web interface where Cyrillic hashtags are fully supported

Current behavior

• Returns error 400 (Bad Request):

InnertubeError: Request to https://www.youtube.com/youtubei/v1/browse?prettyPrint=false&alt=json failed with status 400
{
  "error": {
    "code": 400,
    "message": "Request contains an invalid argument.",
    "errors": [
      {
        "message": "Request contains an invalid argument.",
        "domain": "global",
        "reason": "badRequest"
      }
    ],
    "status": "INVALID_ARGUMENT"
  }
}

Version

Default

Anything else?

No response

Checklist

• I am running the latest version.
• I checked the documentation and found no answer.
• I have searched the existing issues and made sure this is not a duplicate.
• I have provided sufficient information.