Earlier quoted context omitted.
Mozilla also recently launched their own version of HIBP that just gets the data from HIBP and passes it to their users: https://monitor.firefox.com/ Though just realised, they're not that upfront about giving HIBP credit - If I were Troy this would peeve me a bit.
I thought the same when I initially was prompted about Firefox monitor at the bottom of Firefox's new tab page. Was a little peeved at what seemed like a copy, but I have now realised it is just building on top of Troy's work [1] which is even better because of Firefox's larger reach. They don't have to have a blinking marque text at the top attributing it to Have I Been Pwned. But they could have mentioned it on the…
If you trust HiBP, you don't really need Firefox Monitor. It was created specifically to reach people that HiBP could not reach.