Section background no longer transparent (.PNG)

Site URL: https://www.cboothandson.co.uk/

Hello, I've have encountered an issue that I'm hoping someone can help with.

If you take a look at my home page you will see a 'happy new year' banner. The banner a PNG. image set as the background with falling snow flakes. I don't know how or why, but for some reason the image in the background seem to no longer a PNG. and there is now a white overlay or backdrop. I have tried all of the things I can think of, altering opacity of overlay in the edit theme settings. to me it seem as though Squarespace for some reason is no longer honoring the PNG. image.

I have added some custom CSS (see below) but I really don't think that that is the issue (I could be wrong!)

.products.collection-content-wrapper .grid-item.hentry.sold-out .grid-image-wrapper {
  opacity: 0.5;
}

Thank you in advance, I really am very confused.

I have logged on this morning and the problem seems to have resolved it's self.

Thanks anyway!