wp_get_block_style_variation_name_from_registered_style( string $class_name, array $registered_styles = array() ): string|null

18function wp_get_block_style_variation_name_from_registered_style( string $class_name, array $registered_styles = array() ): ?string {19	if ( ! $class_name ) {20		return null;21	}22 23	$registered_names = array_filter( array_column( $registered_styles, 'name' ) );24 25	$prefix = 'is-style-';26	$length = strlen( $prefix );27 28	foreach ( explode( ' ', $class_name ) as $class ) {29		if ( str_starts_with( $class, $prefix ) ) {30			$variation = substr( $class, $length );31			if ( 'default' !== $variation && in_array( $variation, $registered_names, true ) ) {32				return $variation;33			}34		}35	}36 37	return null;38}