I don't know if this is specific to the backup plugin, but something that caught my attention is that every message logged to the clightning log from the plugin appears twice. Once prefixed with root (no, that is not the username) and once plain. For example:

2021-03-01T09:18:47.426Z INFO    plugin-backup.py: root        : Versions match up
2021-03-01T09:18:47.427Z INFO    plugin-backup.py: Versions match up

(low priority issue, just somewhat spammy)