Photon use custom CDN.

index.php

<?php
$cdn_image_domain_to_use        = 'https://{replace-me}.cloudfront.net'
$cdn_image_domain_to_use_parsed = wp_parse_url( $cdn_image_domain_to_use );

// Stop creating crops and just use the original image.
add_filter( 'jetpack_photon_noresize_mode', '__return_true' );

// Setup custom domain.
add_filter( 'jetpack_photon_domain', fn() => $cdn_image_domain_to_use );

// Trick jetpack to use our domain. See https://github.com/Automattic/jetpack/blob/946220362c7db84cad03c7fae4c76c5930b46fd5/projects/packages/image-cdn/src/class-image-cdn-core.php#L163-L175
add_filter(
	'jetpack_photon_pre_image_url',
	function ( $image_url ) use ( $cdn_image_domain_to_use_parsed ) {
		// Replace host with cloudfront.
		$parse_url = wp_parse_url( $image_url );

		return str_replace( $parse_url['host'], $cdn_image_domain_to_use_parsed['host'], $image_url );
	},
	20
);