If it's all one codebase that isn't split for deployment, it's still very much a monolith. The distinction between monolith and microservices isn't how many deployments you have, it's how many deployment units. If the app is stateless, replication is strictly an operations concern, so from a developer perspective a single stateless deployment unit is a monolith.

An org might deploy a complete copy of the monolith for a single tenant, and it would still be a monolithic architecture.

Monolith refers to the application. It’s in contrast to a services architecture.