Facebook processes the product images and adjusts them to their requirements, having the wrong ratio can result in a skewed image.
Image size requirements
For carousel ads, collection ads and Shops: Product images display in square (1:1) format. The minimum image size is 500 x 500 px. We recommend 1024 x 1024 px for best quality.
For single image ads: Product images display at a 1.91:1 aspect ratio. The minimum image size is 500 x 500 px. We recommend 1200 x 628 px for best quality.
Image cropping settings
You can choose how your product images will be cropped in the Settings tab of Commerce Manager under Catalog. Image cropping settings apply automatically to all products in your catalog. You can apply image cropping to:
Ads: Ads using carousel and collection format.
Single image ads: Ads using single image format.
Product page (Instagram only): Product pages that display when people tap on a product in shops on Instagram. Note: Images won't be cropped anywhere else in shops on Instagram. Images won't be cropped at all in shops on Facebook.
There are three cropping options:
Fill frame with image (default): Zooms in on the product image to fill the entire frame.
Show entire image in frame: Shows the entire product image within the frame. White space may be added around the image.
Crop and resize image to fit frame: Crops and resizes the image to fit the entire product in the frame. This works best with white or transparent backgrounds.
Select Save to apply your settings.
For more information, read Product Image Specifications for Catalogs on Facebook.