If your application is stateless following your definition then it's trivial to break the monolith down to microservices that focus on a bounded contexts while sharing a common db. This is a very well known microservices pattern.
Strong module boundaries
Independent deployment
Technology diversity
And with a single database you severely limit the benefits from strong module boundaries and independent deployments. Suddenly you have to synchronize deployments, and anyone can pull or change any data in the database which now must be enforced with discipline which gets you into the same boat as a monolith.
Only worse because you don't have tools (IDEs, linters, etc) telling you what parts of the code have to be changed.