"Upcoming notification permission changes in Firefox 72" https://hacks.mozilla.org/2019/11/upcoming-notification-permission-changes-in-firefox-72/
It seems like a good idea to require a user gesture before showing the notification prompt. So you'll have to actually click a button or something on the web page before Firefox will show the prompt.
Upcoming notification permission changes in Firefox 72 – Mozilla Hacks - the Web developer blog
Earlier this year we decided to reduce the amount of unsolicited notification permission prompts people receive as they move around the web using the Firefox browser. This is an intrinsic ...