Of course not. Please read [[Web Push notifications in Firefox]] and disable it.

''<p>rmacdona55 [[#question-1540560|said]]</p>'' <blockquote>I'm getting these notifications today, supposedly from Firefox. Are they legit? Thanks </blockquote> They are not from the Firefox web browser nor from Mozilla. They are from sites you have allowed to send you notifications. Instead of useful information some sites may send you junk, spam, fake virus/trojan alerts etc. You can revoke these sites as explained in KB article link in above reply.