Not true, I’m a work from home consultant and use slack calls vie Firefox several times a day without a problem even after the Quantum update

"Doesn't support" does not mean "doesn't work". It just means that if you have a problem with slack on Firefox that doesn't happen in Chrome, they will not go out of their way to fix it and, probably, that they don't test slack on Firefox (or not as much as they test it on Chrome).

I should have been more clear. I meant that it doesn't work. I get a message saying that I should use chrome. I'll get a screenshot and update here.

Here is their doc: https://get.slack.help/hc/en-us/articles/205138367-Common-is...