Those are aircraft-induced cirrus clouds.
Aircraft-Induced Clouds (AICs), colloquially called contrails, form from the emission of soot from jet engines during cruise flight in favorable atmospheric conditions. AICs absorb, scatter, and reflect shortwave and longwave radiation. This radiative transfer has a cooling effect during the day; however, the night experiences an overwhelming warming effect, which leads to an overall warming effect on Earth, contributing to anthropogenically propelled climate change.
https://www.mdpi.com/2073-4433/13/8/1257
Clouds created by aircraft have a bigger impact than the emissions they emit
If the conditions are right, these ice crystals grow and spread across the sky as a cloud. This happens when a plane travels through an area where a cloud was waiting to form, with the ice crystals forming behind the plane, triggering the formation of a larger cloud.
https://www.imperial.ac.uk/news/242017/clouds-created-aircraft-have-bigger-impact/