Query on upload to s3 bucket NodeJS

Yes, TLS is expected to be used.

The following AWS official documentation and the AWS official blog state that TLS is used by default in the AWS SDK for JavaScript. [1] [2]

[1] Enforcing a minimum TLS version - AWS SDK for JavaScript
https://docs.aws.amazon.com/sdk-for-javascript/v3/developer-guide/enforcing-tls.html
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AWS SDK for JavaScript v3 automatically negotiates the highest supported TLS version for a given AWS service endpoint.
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[2] TLS 1.2 to become the minimum TLS protocol level for all AWS API endpoints | AWS Security Blog
https://aws.amazon.com/jp/blogs/security/tls-1-2-required-for-aws-endpoints/
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If you are one of the more than 95% of AWS customers who are already using TLS 1.2 or later, you will not be impacted by this change. If you are already using TLS 1.2 or later if your client software application was built after 2014 using an AWS Software Development Kit (AWS SDK), AWS Command Line Interface (AWS CLI), Java Development Kit (JDK) 8 or later, or another modern development environment.
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I hope the above is helpful.