On a product template page, there is the product with images, details, and add-to-cart components. Below is a collection list with products in the same category as the current product excluding the current product.
When selecting a variant option in the add-to-card component, the product image changes to reflect the selection.
The bug is that this is also changing the main image in the other products (related products) on the same page. So for instance, selecting the blue color variant of the product is changing all product images on the page to the same current product’s blue shirt image.
Here’s a video to show it in action.