fix(incoming): 解决存量缓冲内容读取失败问题

[RobinzZH]

Checklist:

• test cases has added or updated
• documentation has added or updated
• commit message follows the convention commit guidelines

[tencent-adm]

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[wikibady]

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[github-actions]

🎉 This PR is included in version 2.6.9 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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