I’m not sure either but it seems to have stopped doing it now.
Even though, I feel there’s improvements that could be made to the icon.
The images below are screenshots taken from my phone of the same source image at the full width of my screen.
Articles addon cover photo, as displayed...
So here's a thing, left image was scaled to 247 x 185 using GIMP, right image is same source image after being set to 247 x 185 in the icon settings.
But there's definitely something funky going on becasue for some reason NOW, when I use the source image it's fine 🤷♂️
OK I think it's more to do with aspect ratio and scaling.
Using 248x185 seems to have helped and I expect some improvements could be made with the source images.
EDIT - I think the product card images would be better if they had a minimum height of 260px though, 185px is a bit on the small...
The images just don't seem clear for some reason.
It's strange as I don't get this issue when using the Articles Mangement System addon with a similar grid view layout.
I'll try experimenting with source image quality, see if that makes a difference.
If I have found the setting you're suggesting, it only allows for adjustment of icon size, which does help with one aspect but not with image resolution.
Suggest improving the imagine quality on icons, resolution seems very low.
Consider including an option to use a specific image as a cover photo, utilising all of the available image space on the product cards and above the product overview.
Image gallery location options - gallery tab view...
Implement a product structure where a single variant can have multiple configurable choices (fields), rather than creating an exhaustive list of every possible variant combination. Allowing the customers to chose a specific combination and see the price prior to adding to the cart.
Examples...