"Then it sends request to users service to get missing information about users" What information would an order need to know about the user except for its ID? S

"Then it sends request to users service to get missing information about users" What information would an order need to know about the user except for its ID? Shipping address? That could have been stored in the order db. Usually there is an orchestration layer above these services such as graphql, that merges all the data together for presenting to the UI. Somewhere there needs to be a defined contract between service boundaries so that internals can be changed without affecting all dependent systems. The db is not a good place for this contract.