Kopia will put a CACHEDIR.TAG file in a blob cache to facilitate skipping its own directory when creating a snapshot, but the file is not present in the base of the cache directory (e.g. ~/.cache/kopia), which results in backups of cli-logs, content-logs and <hash>/server-contents. While I feel that none of these should be backed up by default, at least the server-contents cache should probably be treated the same way as the blob cache, because it is large and redundant with the contents of the backup itself.