Source

File: wp-includes/class-wp-block.php

public function __get( $name ) {
		if ( 'attributes' === $name ) {
			$this->attributes = isset( $this->parsed_block['attrs'] ) ?
				$this->parsed_block['attrs'] :
				array();

			if ( ! is_null( $this->block_type ) ) {
				$this->attributes = $this->block_type->prepare_attributes_for_render( $this->attributes );
			}

			return $this->attributes;
		}

		return null;
	}