Timestamp Discrepancy Between C++ REST Client and JavaScript REST Server on Same Machine

I have a C++ REST client and a REST server running in Chrome as a JavaScript code. Both the client and server are running on the same Windows machine. However, I’m encountering a strange issue where the request received time on the server is earlier than the request sent time from the client.

Here’s a snippet of my server-side JavaScript code:

const recievedTime = performance.now();
        const timestamp = new Date(
            performance.timeOrigin + recievedTime
        ).toISOString();

And here’s a snippet of my client-side C++ code:

        // Get the current time point.
        auto now = std::chrono::system_clock::now();

        // Convert to time_t for formatting.
        std::time_t currentTimeT = std::chrono::system_clock::to_time_t(now);

        // Get the local time components (single argument to std::localtime).
        std::tm localTime = *std::localtime(&currentTimeT); // Dereference the returned pointer.

        // Create an ostringstream for formatting.
        std::ostringstream formattedTime;

        // Use put_time for efficient formatting.
        formattedTime << std::put_time(&localTime, "%Y-%m-%d");
        formattedTime << 'T';
        formattedTime << std::put_time(&localTime, "%H:%M:%S");

        // Get fractional seconds with nanosecond precision.
        auto duration = std::chrono::duration_cast<std::chrono::nanoseconds>(now.time_since_epoch());
        int64_t fractionalSeconds = duration.count() % 1000000000;

        // Format milliseconds with 3-digit precision.
        formattedTime << '.' << std::setfill('0') << std::setw(3) << (fractionalSeconds / 1000000);

        // Append 'Z' for UTC time zone.
        formattedTime << 'Z';
        std::string timeStamp = formattedTime.str();

I’m expecting the server to receive the request with a timestamp that matches or is later than the timestamp generated on the client. However, I’m observing that the server’s received time is earlier.
Client sent time : 2024-03-12T09:38:03.404Z
Server receive time : 2024-03-12T09:38:03.398Z

Could someone help me understand why this discrepancy might be happening? Is there an issue with how I’m generating or handling timestamps in either the C++ client or JavaScript server code?