One thing I remember hearing about in 2020 was that large ships moved away from high sulfur fuel. This meant that suddenly their fumes were seeding fewer clouds over the ocean and consistently clearer skies were seen immediately afterwards. It was a big affect in the Atlantic and contributed to a degree or so more heating.
Surprised I haven't heard more about it as it seems like it could have huge implications for climate change.
I read an article about that last year. There are studies (a study?) going on to see how the changes have affected the trails and seeding you mentioned.