I don't think a place like that exists I think OP's friend is just lying to them to excuse why they got fired. I've never heard of a company with unlimited holidays but then fire somebody for taking them.
Nah, ey were not fired (yet?) and I also worked there before unlimited vacations became a thing, so I kinda think they may went that way. As was said somewhere around this comment with unlim you can guilt/fear your employees into working more and then not pay them unspent days.
Where is this? What is the point in guilt in your employees to work in longer hours when you can just contract them to work longer hours perfectly legally?
Also, I guess there are some fine print conditions like you get less bonuses if you're not working enough, or you're only eligible after working for some time. But that details I don't know