Product gallery image problem

Found a solution from one of the old thread, hope it may help you fix this issue

/**

Fix for single product image sizes
*/
if ( ! function_exists( 'woodmart_single_product_image_sizes') ) {
function woodmart_single_product_image_sizes() {
$sizes = wc_get_image_size( 'woocommerce_single' );
if ( ! $sizes['height'] ) {
$sizes['height'] = $sizes['width'];
}

	return array( $sizes['width'], $sizes['height'] );
}

add_filter( 'woocommerce_gallery_thumbnail_size', 'woodmart_single_product_image_sizes' );
}

For more info, you can refer
https://www.ads-software.com/support/topic/after-update-to-3-5-0-product-variation-images-size-changed/ and
https://github.com/woocommerce/woocommerce/issues/21646