Do I need to add `--compression` to `copy` and `prune`?

If I use copy to copy snapshots from a repository whose snapshots are created with backup --compression max to another repostiory, do I need to add --compression max, so that the snapshots still have maximum compression?

Also, when I run prune command on my repositories, do I need to add --compression max?

If --compression max is not specified, it’s auto by default. I don’t know if prune and copy change the compression of the data to auto.

You have to specify --compression max. prune and copy decode and reencode (using the compression level specified for the current operation) all copied data.