I've seen them often on the UK - Far East routes. Taken some video and still not sure what they are.
I've seen plenty of Starlink - I'm sure it's not Starlink. they move in ways that not seem possible with technology that I am aware of, but maybe that's the point, its tech that is being developed by th military that we have no idea about.
In all I've seen them about 6/7 times, with different colleagues who all saw them to.