Fix object-fit/featured image block bug introduced in WP 6.0.3

safe-css-featured-image-block-fix.php

<?php
/**
 * Plugin Name: Featured Image block bugfix for WP 6.0.3
 */

namespace PWCC\SafeCSSFeaturedImageBlockFix;

/**
 * Add object-fit to supported CSS properties.
 *
 * This works around a bug introduced in WP 6.0.3 that caused the object-fit
 * property to be stripped from CSS in the featured image block.
 *
 * @see https://core.trac.wordpress.org/ticket/56855
 *
 * @param array $properties CSS properties considered safe by KSES.
 * @return array CSS properties modified to include object-fit.
 */
function safe_css( $properties ) {
	$properties[] = 'object-fit';
	return $properties;
}

add_filter( 'safe_style_css', __NAMESPACE__ . '\\safe_css' );