By default, when you create a Product data export in EZ Exporter and select the images.src field (list of all product Image URLs), the URLs will be exported in one column separated by a comma for each product.

To change the comma separator to a semicolon, you can use the Calculated Fields section instead with this formula (this will create a copy of the images.src field and automatically replace the comma with a semicolon, so you can de-select the original from the "Fields" section):

{{ images.src }}.replace(",", ";")

In case you'd like to put the image URLs in separate columns, please see our guide here.