Within the NoSQL domain, ScyllaDB and MongoDB are two totally different animals. Its simple adoption and extensive community/ecosystem have made it the de facto standard for getting started with NoSQL and powering countless web applications.
Moreover, while MongoDB offers the option of enforcing schema validation before data insertion, ScyllaDB requires that data adhere to the defined schema.
It’s important to note that even queries that follow performance best practices will behave differently on MongoDB than on ScyllaDB.
MongoDB adoption is flat, but MongoDB is certainly here to stay because it has some really interesting features.