They are called contrails, it's produced by an aircraft's engines or changes in air pressure, mainly, they are line shaped vapors coming out of a plane's engine, it's completely normal, as long as it's a white contrail it should be fine. but if it's gray, then that is smoke. And ithe engine might be burning.
@SlavicUnionist Ok, thank you for your answer
They are called contrails, it's produced by an aircraft's engines or changes in air pressure, mainly, they are line shaped vapors coming out of a plane's engine, it's completely normal, as long as it's a white contrail it should be fine. but if it's gray, then that is smoke. And ithe engine might be burning.