I've seen them do all of the above.
Leave horizon to horizon trails. Some straight others pushed by high altitude winds.
Leave trails that slowly or rapidly fade.
Leave no trails at all.
This has been consistent since the 70's in my personal experience. The only thing that has changed up here is that the long-range routs are different, there's fewer over my city now.
Contrails aren't just water vapor and could do the same thing making it hard to tell.
I remember when contrails didn't do this.
Must be Global Warming, huh?
That's my experience. Contrails just chilled in the same spot and slowly faded away. They didn't spread.
I've seen them do all of the above.
Leave horizon to horizon trails. Some straight others pushed by high altitude winds.
Leave trails that slowly or rapidly fade.
Leave no trails at all.
This has been consistent since the 70's in my personal experience. The only thing that has changed up here is that the long-range routs are different, there's fewer over my city now.
I think the first one I noticed was after I started roofing around 2018.
I remember tons of trails from growing up outside in the 90s but I never saw anything like that back then.