The custom bundle image is too big. How can I reduce the custom bundle image size?
Bundler will show the custom bundle image in it's original size. So if your original image is 500px wide, the maximum width of the image will be 500px, but the actual size will depend on the available space. If you are using Shopify to host your image, then you can change the dimension of the image by adding the width and height values at the end of the image url.

For example, if an original image file url is:
https://cdn.shopify.com/s/files/1/1111/1111/1111/files/image-name.jpg
You can change the width of the image to 400px and height to 400px, by adding the _400x400 parameter right before the image suffix (.jpg or .png).
https://cdn.shopify.com/s/files/1/1111/1111/1111/files/image-name_400x400.jpg