Why my logo and promotion picture of my chrome extension are pixelated?

I have just launched a chrome extension and cannot figure out those two points :

1. Why on the web chrome store my logo looks like pixelated (on my laptop uploaded image was good...), here how it's look like :

2. Why my promotional picture doesn't use promotional pictures I have uploaded but use my icon :

Hope somebody has already tackled this issue !

Here my extension : https://chrome.google.com/webstore/detail/emoji-keyboard-emoticons/mokaebkcdjejgknjpmdpcphgkoebiodg

Thanks !

make sure to upload the 440 pixels promo img in the dashboard, as this is the one that should be used in your second question