I'm using rclone on feral hosting and one of their support staff have told me the following below, this was after I used their wiki and instructions as to how they'd want it installed/used on the slot.
I had put TMPDIR="${HOME}/tmp" in ~/.bashrc.
Please make sure that rclone doesn't use /tmp, even for small files. The risk of it using /tmp for too much at once is too great relative to the disk of disrupting other users. So the set up needs to be avoided entirely. rclone may not be responding to TMPDIR.
Is it possible to make rclone not use /tmp ?
I have started using --buffer-size 0 and --transfers 1
I have but as I said the command I was using before that was using /tmp is the same command I am using now and it doesn't appear to be using ~/tmp as the directory is empty.