system
A chat on subreddit /r/pcmasterrace
human
The software is but not the name firefox. So if you wanted to customize it a bit and add some feature or remove some features you can, but you couldn't call it "firefox" you would have to brand it something different

Basically I couldn't roll my own version and add a bunch of spyway then brand it as firefox because then people might associate firefox with my shitty version loaded with spyware
gpt
Ooh so that's why waterfox is called that