Rds module issue with custom_iam_instance_profile parameter set to null or empty

Hi i’m using terraform aws module Terraform Registry

when i call it in my terraform code like :
module “mysql” {
source = “terraform-aws-modules/rds/aws”
version = “6.3.0”
identifier = “{var.cluster_name}" username = var.master_username password = var.master_password engine = var.db_engine_name engine_version = var.db_engine_version port = var.port instance_class = var.instance_class multi_az = var.multi_az subnet_ids = var.subnets_private_db vpc_security_group_ids = var.security_group_ids storage_type = var.storage_type allocated_storage = var.allocated_storage iops = var.iops snapshot_identifier = var.rds_snapshot_identifier skip_final_snapshot = var.skip_final_snapshot final_snapshot_identifier_prefix = "{var.cluster_name}-rds-finsnap-${random_password.backup_name_suffix.result}”
apply_immediately = var.apply_immediately
backup_retention_period = var.backup_retention_period
backup_window = var.backup_window
ca_cert_identifier = var.ca_cert_identifier
create_monitoring_role = var.create_monitoring_role
monitoring_role_name = var.monitoring_role_name
monitoring_role_arn = var.monitoring_role_arn
monitoring_interval = var.monitoring_interval
cloudwatch_log_group_retention_in_days = var.cloudwatch_log_group_retention_in_days
create_cloudwatch_log_group = var.create_cloudwatch_log_group
enabled_cloudwatch_logs_exports = var.enabled_cloudwatch_logs_exports
create_db_subnet_group = var.create_db_subnet_group
db_subnet_group_description = var.db_subnet_group_description
db_subnet_group_name = var.db_subnet_group_name
db_subnet_group_tags = local.default_tags
custom_iam_instance_profile = var.custom_iam_instance_profile
kms_key_id = var.kms_key_arn
max_allocated_storage = var.max_allocated_storage
parameter_group_name = var.parameter_group_name
parameters = var.parameters
performance_insights_enabled = var.performance_insights_enabled
performance_insights_kms_key_id = var.performance_insights_kms_key_id
performance_insights_retention_period = var.performance_insights_retention_period
publicly_accessible = var.publicly_accessible
create_db_option_group = var.create_db_option_group
major_engine_version = var.major_engine_version
family = var.family
tags = local.default_tags

i have issue like │ Error: invalid value for custom_iam_instance_profile (must begin with AWSRDSCustom)

│ with module.mysql.module.db_instance.aws_db_instance.this[0],
│ on .terraform/modules/mysql/modules/db_instance/main.tf line 51, in resource “aws_db_instance” “this”:
│ 51: custom_iam_instance_profile = var.custom_iam_instance_profile

i tried to set var.custom_iam_instance_profile to “” or null