My first experience with rsync.net was very disappointing. To this day they still advertise “append-only mode” support for restic at https://www.rsync.net/products/restic.html.

Their support people confirmed it doesn’t work (though they didn’t seem to understand why it would be fine for them to support it as advertised...) yet 6 months later they still advertise that they support it, even when I have e-mailed to remind them (and it still doesn’t work either) :(