It is “backwards” from some other commands — usually you run copy/rsync/link from source to destination, but with tar the destination (tarball) is specified before the source (directory/files).
That, and the flags not needing dashes always just throws me for a loop.
And the icing on the cake is that I don’t use tar for tarring that often, so I lose all muscle memory (untaring a tgz or tar.bz2 is frequent enough that I can usually get that right at least…).
Same — rsync to a pi 3 with a (single) ZFS drive at family’s house. Retain some daily/weekly/monthly snapshots.
I have a (free) VPS with static IPv4 which is how I connect everything.
Both the VPS and the remote site have limited network speed (I think 50Mbps for VPS), so the initial sync was done sneakernet (well…“airplane net”). Nightly rsync is no problem bandwidth-wise, and is mostly just any new videos I’ve uploaded to my local Immich instance.