I'm confused by this limitation on disk cloning. Earlier on, it says You can also delete the source disk without any risk of deleting the clone. The ability to clone disks is useful for duplicating production data to debug without disturbing production This makes me think that they are segregated and safe.
But further down, it says You can create at most 1000 total disk clones of a given source disk.
If I clone a clone, does that count against the original source, or just against Clone 1's limit? Are there any other ways that these are entangled with each other?
https://cloud.google.com/compute/docs/disks/create-disk-from-source
No, it does not count the original source and you can also clone the newly cloned disk again with the 1000 limit as it will be treated as an original.
The one that is related to an original image would be the Snapshot and it reflects the contents of a persistent disk in a concrete instant in time.
Snapshots are also less expensive than Cloning as it uses less disk space and is good for a quick backup and restore. Using snapshots may be simpler for most cases.