When I uploaded a photo for the main product photo in avif format, I saw the following happening. It is displayed in the source code of the product page, but when I go in to edit the product, the photo does not appear so I can go in and put alt text, etc.
Thanks for reaching to us and appreciate your patience.
Could you please check how it works with some default WordPress themes like TwentyTwenty or WooCommerce Storefront to understand if it is our theme’s issue or not?