Is it safe to use default permissions for spaces as public?

I want to use DO spaces for storing Pdf files for an Android Application, I’m using Google Firestore Database for my App, so I don’t want to go with S3 compatible API to access these files instead I’ll store the file URL to Firestore Collection for this I have to set the DO spaces permission to Public. So, I don’t know whether it’s safe or not? Any suggestions will be appreciated. Thanks