I wanted to block our users from installing Monterey until we get a chance to test it in our environment.
So I downloaded and launched the installer, then opened Activity Monitor to get the process name.
The installer showed up as:
Install macOS Monterey
But when I tried blocking that process (with Restrict exact process name checked), it didn't work.
On a hunch I changed it to this:
Install macOS Monterey.app
That worked.
I'm not sure why this is the case, because there's definitely no .app in the process name.