It’s ordered by course started. So if you have multiple courses and start Course A, then Start course B, then Course C the order is C B A…. and that doesn’t change even if you last watched a lesson in Course A.
I guess ideally you’ve have a sort by dropdown – last watched, course started, course progress etc. It’s not really much of an issue unless you have started 20+ courses and are switching between them but this begs the question… why?