Today I learned that unprivileged users can run "systemctl show servicename" to see all the environment variables set in the .service file.
This means if someone sets their AWS_SECRET_ACCESS_KEY in there (or any other secret), it can be read by an attacker even if they don't have read privileges to read the .service file.
For defenders, use EnvironmentFile= instead of Environment= and as long as your environment file has the correct privileges, you will be fine on this front.
I don't like Systemd but I find it hard to find a distro for desktop/laptop that is not Systemd as I find many of my options there to be a PITA to work with.
Linux geeks doing what Linux geeks do...