New compression options were added in rsync 3.2. From https://download.samba.org/pub/rsync/NEWS#3.2.0 https://download.samba.org/pub/rsync/NEWS#3.2.0 Various

New compression options were added in rsync 3.2. From https://download.samba.org/pub/rsync/NEWS#3.2.0 https://download.samba.org/pub/rsync/NEWS#3.2.0 Various compression enhancements, including the addition of zstd and lz4 compression algorithms and a negotiation heuristic that picks the best compression option supported by both sides.