[I work at Firebase, but opinions are my own]
I am happy to report that Firebase is actually used by companies of all sizes and types, including Fortune 1000.
Fortune 1000 and fart apps aren't mutually exclusive, to be fair. Look at how many fart apps Google themselves create and then throw away soon after[1]. It is one thing to toss anything you can come up with into the wind to see what sticks during the gold rush, but that doesn't last forever.
[1] https://killedbygoogle.com