Wow. And looking at it, it appears blurry and slightly pixelated, as if it has been upscaled. It also looks like it might have jpeg artifacts from a previous compression. Although it cannot simply be made a jpeg as-is because it is largely transparent. I used https://tinypng.com/ lossy png to get it down to 770kB with virtually no loss of quality (since the quality was so bad to begin with). But it could be shrunk more by either using a smaller image and upscaling it in the browser (instead of upsaling it prior to saving), or merging the background gradient with the image and saving it as jpeg.