Mystery of Zoom auto-restarting, how do I stop it?

I'm running an ordinary Debian system on which I have installed Zoom. After using Zoom, and quitting, the program keeps restarting. After I kill it I use ps to check and it is gone, after about 15 minutes it returns, I kill it again, and later it returns... When it restarts it always has a ppid of 1 (init). I have checked cron, init.d, systemd and all my dot files and there is no trace of anything that can restart Zoom. What can be doing it? How does it do it? I know it's not really a big deal but it is driving me mad and I want to understand how it happens _and_ I would like it to disappear except when I want to use it.