Isn't this (tmpfs for /tmp) the default setup for most OSes, and surely raspberry's homegrown OS too?
Be careful to check inside your docker containers also. It can end up different.
Here is a good article btw, with someone advocating for moving to tmpfs https://ubuntu.com/blog/data-driven-analysis-tmp-on-tmpfs
In fact, I didn't notice the change until now.
Copying through /tmp is a frequently used method for transferring files between users on a multi-user computer.
It is said that the Linux kernel will include soon an improved version of tmpfs, which will allow user extended attributes, within certain limitations.
When this will happen, one of the most annoying misfeatures of tmpfs that has persisted for much too many years will finally be gone away.