Do I need to encrypt Firebase DB separately?

I'm trying to create a notepad app using Firebase DB, but when I used it, I could see other people's data and storage pictures without data encryption.

In Firebase, it is considered that security supports protecting data by placing access restrictions on users who are not authenticated through user authentication.

Other encrypted server DBs can also be viewed if the developer wants to see them, so I think external security is the same as what the developer can seeOnly

Can I use Firebase DB without encryption?