Pixelated custom collection images (Trade Theme)

I’m using the new Trade theme, and have uploaded a banner to each collection to display across the site (collection list on homepage, collections grid and individual collection pages).

They are the correct size and resolution to display on a wide screen, so they aren’t being enlarged (and they’re not massive file-sizes, all under 500kB). I suspect I have to adjust some code to make them display at the correct resolution, but I cannot find it or fix it. I’d love some help – there isn’t much support yet for this theme. It’s hard to see from the pics, but you can see the size/res of the original image, then the pixelation at 2 different sizes.

If you used Canva or something similar to create the banner, I would suggest downloading the image in SVG format and trying again. Usually SVG format images don’t have this isssue

Thank you – this worked, sort of. The files sizes are much larger, but I guess there will be less of them. I am getting an error when uploading the images now. I can do some of them, but not all of them. it’s not file size (I could upload the larger one), no idea what the issue is. I’ve downloaded them from Canva as a batch, so there shouldn’t be an issue between files.