There are a few issues here:
– Remove the text from the image
– I think if you’re going to use the picture element you need a media attribute. So your retina requirements won’t work here. Replace it with an img tag with your srcset attribute and src fallback. Scratch that, you can do it the way you’ve done it, but you’ll need to replace the srcset attribute on the img tag with src for it to be a proper fallback.
– Some of your other pictures look good. I assume they were optimised in the same way. Maybe it was just the photo that’s the issue.