The code is written in a functional language... I have yet to encounter a single mutable variable. However, it is constantly poking at a database, and different

The code is written in a functional language... I have yet to encounter a single mutable variable. However, it is constantly poking at a database, and different modules communicate with each other asynchronously over a message queue. Sounds like Elixir. I'm also on a similar project but I thank my stars that I don't also have to worry about mutable state at the micro-level, and that I can chisel away at my small corner of the monolith with blinders on and not worry about messing up other corners of the codebase via spooky action at a distance. Sometimes, your domain/business logic itself is just really complicated and can't get simplified without domain level (re)organization and that's hard as feature requests pile in and make your codebase more and more complicated.