Take this as an example: https://en.wikipedia.org/wiki/File:Price_discrimination_(third_degree).svg
The 800px one renders just fine: https://upload.wikimedia.org/wikipedia/commons/thumb/f/f8/Price_discrimination_%28third_degree%29.svg/800px-Price_discrimination_%28third_degree%29.svg.png
The 1024px one has strange black regions in it and is wrong: https://upload.wikimedia.org/wikipedia/commons/thumb/f/f8/Price_discrimination_%28third_degree%29.svg/1024px-Price_discrimination_%28third_degree%29.svg.png