Is Medplum self hosted on AWS is multi tenant? Each project is isoloated at DB level(seperate DB for each project)?

Yes - Multi tenant, i.e. projects are in the same DB - here's a diagram https://www.medplum.com/docs/auth/user-management-guide#background-user-model

Thanks, yes thats what I thought, but got confused with line https://www.medplum.com/docs/access/projects#:~:text=Projects%20can%20provide%20each%20of%20these%20partners%20their%20own%20isolated%20environments where I thought isoloated environments means seperate DB as well