[0] https://docs.microsoft.com/en-us/dotnet/architecture/contain...
This would also mean that deploying a microservice architecture onto a single server, using docker for example, would be considered a monolith. Or even better, any application that leverages a database on a separate server is no longer a monolith! That's way easier than rearchitecting your whole app.
I've never come across a definition for monolith in the context of software that had anything to do with the actual infrastructure employed
It's like saying "this thing says it is built as a suspension bridge, but there are ten of them, so I wouldn't call it a bridge."
Microservices on the other hand in theory have a number of very small services that at most share some libraries, but can be deployed independently and could each even be written in different languages if you want. This mostly is an advantage if you know that different portions of your app are gonna scale very differently from each other and rely on disparate data models as well and only share a small interface. In practice, things frequently don't end up as clear cut as you expected on the outset and you end up having to heavily coordinate many of your deploys across services.