Is it a bad idea to use Firebase with Anonymous Authentication?

I am doing a thing on my website where users can enter a "thought" with their name (optional) and they can see if anyone has ever had the same thought before. I was thinking of using Firebase with anonymous authentication to store these thoughts but I am worried that it will open up my database to malicious attack. Anonymous authentication seems to allow anyone to change the database. Is that true? I don't want some random jerk to be able to delete my database or something like that... If a user can do that, then how or what can I use where it allows anyone to be able to submit a thought via my site while still preventing malicious activity?

Thanks, Zach