Based on amazon docs:
An Amazon ECS cluster is a logical grouping of tasks or services. If you are running tasks or services that use the EC2 launch type, a cluster is also a grouping of container instances. If you are using capacity providers, a cluster is also a logical grouping of capacity providers. When you first use Amazon ECS, a default cluster is created for you, but you can create multiple clusters in an account to keep your resources separate.
In our use case, we are not using EC2 launch types. We are mainly using Fargate.
What are the usual basis/strategy on grouping services? Is it a purely subjective thing?
Lets say I have a Payment Service, Invoice/Receipt Service, User Service, and Authentication Service. Do I put some of them in an ECS cluster or is it best practice to have them on separate ECS clusters.