Landing, there is hardly any disturbed air behind the engines. While modern engines don't produce all that much smoke they do produce lots of heat when running

Landing, there is hardly any disturbed air behind the engines. While modern engines don't produce all that much smoke they do produce lots of heat when running at full power, leaving a tell-tale trail of visibly disturbed air and exhaust gases behind them. No such trail is visible here so the engines are at a low power setting (idle or close to it).