A tab in vscode has a dot in it if the contents are modified since last save.
If a save is complete, that dot will go away. If there is no dot, the file is unmodified.
Speaking of which, it also changed the decades old symbol for unsaved files (an asterisk) for no discernable reason. Given that it also doesn't save on loss of focus it led to my many WTFs when I first started using it.
VSCode does not indicate to the user when the save is complete. I've had saves require 15+ seconds, and they are not atomic, so you must be careful to not use the file (compile, git, etc) until the save is finished, which is hard to know. I've personally lost data this way.
I agree that command palette is great and is clearly a point of convergence among new apps. I wish Apple would embrace it!