Oh "rclone copy" apparently doesn't force a sync to disk. And if you're running it a server with e.g. 512GB of RAM than this can result in a ":wq" in vim to appear as if it froze.
Is vim forcing a generic sync to disk when it exists? Or is this some kind of kernel bug that it doesn't just force that one file to sync to disk and instead waits for everything currently pending to be written?
What's going on here exactly?!?