Azurerm_cosmosdb_account capabilities unclear

We are maintaining an azurerm_cosmosdb_account via terraform. We currently run Mongo Server Version 4.0.

resource "azurerm_cosmosdb_account" "cdb" {
  name                = local.cosmos_database_account
  resource_group_name = local.resource_group_name
  location            = local.location
  offer_type          = "Standard"
  kind                = "MongoDB"
  mongo_server_version = "4.0"

With the capabilities we also specified

  capabilities {
    name = "MongoDBv3.4"

and I have no clue what this does and I cannot find any documentation, neither with Terraform or Microsoft Azure what this is all about. For me this looks like an outdated artifact because the server version is now specified directly via “mongo_server_version”. Consequently, I tried to remove this capability but the plan says this would destroy our resource, which does not make sense to me.


So my question is: What does this capability do and why would it force a recreate?