Source

File: wp-includes/rest-api/endpoints/class-wp-rest-block-directory-controller.php

public function get_collection_params() {
		$query_params = parent::get_collection_params();

		$query_params['context']['default'] = 'view';

		$query_params['term'] = array(
			'description' => __( 'Limit result set to blocks matching the search term.' ),
			'type'        => 'string',
			'required'    => true,
			'minLength'   => 1,
		);

		unset( $query_params['search'] );

		/**
		 * Filter collection parameters for the block directory controller.
		 *
		 * @since 5.5.0
		 *
		 * @param array $query_params JSON Schema-formatted collection parameters.
		 */
		return apply_filters( 'rest_block_directory_collection_params', $query_params );
	}