Amazon web services – Terraform RDS upgrade from 10 to 14

I am upgrading my RDS postgresql from 10.21 to 14.4 by creating a new family group as well , my idea is to create new family group and upgrade the rds with new family group and then delete the old family group (deleting the old family is not that important as I know that cost money ), I get an error , please check my code

My terraform version is 0.13.7

module "rds_pgsql" {
  source = "./modules/aws-rds-pgsql"

  stack                               = var.stack
  environment                         = var.environment
  app_name                            = var.app
  description                         = var.app
  db_username                         = data.aws_kms_secrets.rds.plaintext["master_username"]
  db_password                         = data.aws_kms_secrets.rds.plaintext["master_password"]
  db_name                             = var.db_name
  security_group_db_access            = flatten([module.db_subnets.cidr_blocks, module.private_app_subnets.cidr_blocks])
  db_param_group_family               = aws_db_parameter_group.rds_parameter_group.name
  db_monitoring_interval              = var.db_monitoring_interval
  db_engine_version                   = var.db_engine_version
  db_instance_type                    = var.db_instance_type
    db_apply_immediately                    = var.db_apply_immediately
  allow_major_version_upgrade         = var.db_allow_major_version_upgrade
  db_backup_plan                      = var.backup_plan_pgsql
    db_backup_retention_period          = 35
    db_backup_window                    = "00:00-02:00"
}

resource "aws_db_parameter_group" "rds_parameter_group" {
  name_prefix = "postgres14"
  description = var.stack
  family      = var.db_param_group_family

  parameter {
    apply_method = "pending-reboot"  
    name  = "client_encoding"
    value = "UTF8"
  }

  lifecycle {
    create_before_destroy = true
  }

  tags = {
    Name        = "${var.environment}-${var.stack}-rds-db-pg"
    Stack       = var.stack
    Environment = var.environment
    Description = var.stack
  }
}

resource "time_sleep" "wait_30_seconds" {
  depends_on = [module.rds_pgsql]

  create_duration = "90s"
}

module code , which has the old db parameter group creation

resource "aws_db_parameter_group" "db_parameter_group" {
  name        = "${var.stack}-${var.app_name}-rds-db-pg-${var.environment}"
  description = var.description
  family      = var.db_param_group_family

  parameter {
    name  = "client_encoding"
    value = "UTF8"
  }

  tags = {
    Name        = "${var.stack}-${var.app_name}-rds-db-pg-${var.environment}"
    Stack       = var.stack
    Environment = var.environment
    Description = var.description
  }
}

error i face

Error: Error deleting DB parameter group: InvalidDBParameterGroupState: One or more database instances are still members of this parameter group events-consents-events-consents-rds-db-pg-gentst, so the group cannot be deleted
    status code: 400, request id: a9cb62d6-7607-4b8d-9d7d-ae9baf4e1f90

i have already added create_before_destroy = true and tried adding the time_sleep as well but still i get the above error , the thing i see is , it first creates the new db parameter group and then start deleting the old db parameter group ,

my expectation is it first creates new db group then upgrade the db instance and then assing the new db group to the instance and then delete the old db group .

Am i missing something or overlooking ??

Thanks

I tried adding

lifecycle { create_before_destroy = true }
and also tried sleep time did not do the magic