Some transparent PNGs are getting a black background when transcoded to webp

Hi there!

We have Cloudflare’s setting that serves images as webp where possible. In the last two weeks, there seems to have been a regression where a small fraction of these images (maybe 2% to 5%) are sometimes getting served with a black background instead of a transparent background.

As an example: has a black background (at least for most POPs I’ve tried), but if we remove image/webp from the Accept header, it serves the correct image without a black background.

Is this a known issue? Is there anything we can do to help debug it and get it fixed faster?

When I look at in Safari, I see that it looks like someone erased the background of the image, so it wasn’t generated as a transparent background PNG. That might be the problem, as the conversion might not be picking out the right transparency mask.

Maybe Support can pass this info along for improvement.

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