Hi there @Alexander413,
Happy to help!
By any change are you using "static/select from catalog" in your product blocks instead of the dynamic option? If so, this would explain the issue as if you select an item from your catalog to display here and then make any changes to the product in Shopify, this product block would've already cached the item with the old image URL so it wouldn't update with the new info and thus cause broken images when sent.
The way to fix this would be to choose the dynamic option (which says it will use your product feed) which is pulling from the catalog at all times and would refresh automatically when you change a product image. Unfortunately, there isn’t a way to do this ‘in bulk’ if you keep the static product block as you would have to be manually create a new product block in every email after any updates to products.
Thanks for participating in the Community!
-Taylor