According to the article at
Pcloud is one of the services that support block-level file copying. This is also fairly clear from the synchronisation times of the official client. For example, updating the tags in MP3 files does not transfer the whole file.
Obviously, having this in rclone would significantly reduce the transfer times and bandwidth usage for file updates.
I was going to create a feature request but decided to first get some feedback here on the forum.
Do any providers in rclone support this? How difficult is it to implement?