<?php

// Insert the following code into your (child) theme's functions.php

add_filter( 'facetwp_builder_item_value', function( $value, $item ) {
	if ( 'personal-photo' == $item['settings']['name'] && !empty( $value ) ) {
		$value = wp_get_attachment_image( $value, 'full' ); // 'full' can be changed to other image sizes
	}
	return $value;
}, 10, 2 );