Programming

Technically, it shares a lot of characteristics with databases. You can put data in there and get data out again later, sure. But it's optimized for short term caching of data, to reduce load on a real database, reduce network requests, that kind of thing.

In programming you can often use tools in ways they were not intended for and it'll still work but the costs of that decision might not become apparent until much later. This is one of those. Over time you'll start to have issues with durability guarantees, complex querying and indexing, transactions and consistency, recovery after failure, backups and restoration, data growth, operational tooling, migrations and schema evolution, concurrency, debugging and observability. None of that shows up during initial development work so you won't notice until you're in way too deep.

Reddis is an in memory cache. Your data will definitely get deleted from Reddis once the amount stored increases or even simply restarting the service. You need proper persistent storage as well so anything that's not in the cache can still be retrieved, albeit slower. Personally, I think NoSQL is overhyped and would recommend Postgres instead, unless your application has some very specific requirements.