wp-content/themes/twentytwentyone/inc/back-compat.php:38Adds a message for unsuccessful theme switch.
voidfunction twenty_twenty_one_upgrade_notice() { echo '<div class="error"><p>'; printf( /* translators: %s: WordPress Version. */ esc_html__( 'This theme requires WordPress 5.3 or newer. You are running version %s. Please upgrade.', 'twentytwentyone' ), esc_html( $GLOBALS['wp_version'] ) ); echo '</p></div>';}Introduced in Twenty Twenty-One 1.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-content/themes/twentytwentyone/inc/back-compat.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.