I actually did that on purpose since all browsers support brotli I risked the possibility someone might have disabled it with an add-on. I wanted to see how many bots that would break. It may not be the most logical process but I just use CanIUse [1] to see what supports Brotli. I ignore the Opera Mini block as they seem to support almost nothing.
Ah, fair enough. Well Firefox should support Brotli by default, so it's probably something going on on my machine.