Is changing the Terraform backend to a different one after the first terraform apply mandatory?

Changing the Terraform backend to a different one after the first terraform apply is optional. The backend in Terraform defines where the state file is stored, which is crucial for managing the infrastructure effectively. Once you have applied your configurations for the first time, you might choose to change the backend if there is a need for improved collaboration, versioning, or state management across teams. However, it isn't a requirement to switch to a different backend.

If the current backend meets the team's needs and there are no significant drawbacks, you can continue using it. This flexibility allows teams to evaluate their options and determine the best backend for their specific circumstances without being mandated to switch upon or after the initial application.