Thanks I have also found a solution. First I am making "GraphAreaToDownload" full screen by adding a section "fullscreen-section" which I am using now to export.

this is component code inside return:

{fullScreen ? 
    (
      <div
        id="areaToDownload"
        className={`${fullScreen && "fullscreen-section"}`} 
        >
          <div 
           style={{ 
              backgroundColor: backgroundColor,
              width: "100vw",
              height: "100vh",
              border: "none",
          }}>
            ..........content to export
          </div>
        </div>
    ) : (...other code)
}

this is css code:

.fullscreen-section{
    display: flex;
    flex-direction: column;
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
    width: 100vw;
    height: 100vh;
    background-color: white;
    z-index: 1;
    border: "none"
}

And it resolved the issue.