reproduce-issue.tf

terraform {
  required_providers {
    mysql = {
      source = "petoju/mysql"
      version = "3.0.24"
    }
  }
}

provider "mysql" {
  endpoint = "127.0.0.1:3306"
  username = "root"
  password = "rootpass123"
}

resource "mysql_user" "user" {
  user               = "dbusername"
  host               = "%"
  plaintext_password = "test_pass"
}

resource "mysql_database" "app" {
  name = "databasename"
}

resource "mysql_grant" "this" {
  user       = mysql_user.user.user
  host       = mysql_user.user.host
  database   = mysql_database.app.name
  privileges = ["SELECT"]
}