fluentd error hostname is tested built-in placeholder(s) but there is no valid placeholder - fluentd

Question

I am trying to setup EFK stack and our environment is as below
(a) ElasticSearch and Kibana runs on Windows machine
(b) FluentD runs on CentOS
I am able to setup EFK and send logs to ElasticSearch and view it in Kibana successfully with default fluent.conf
However, I would like to create indexes using the format ${record['kubernetes']['pod_name']} and I created a ConfigMap as follows
#include "#{ENV['FLUENTD_SYSTEMD_CONF'] || 'systemd'}.conf"
#include "#{ENV['FLUENTD_PROMETHEUS_CONF'] || 'prometheus'}.conf"
##include kubernetes.conf
##include kubernetes/*.conf
<match fluent.**>
# this tells fluentd to not output its log on stdout
#type null
</match>
# here we read the logs from Docker's containers and parse them
<source>
#type tail
path /var/log/containers/*.log
pos_file /var/log/containers.log.pos
tag kubernetes.*
read_from_head true
<parse>
#type json
time_format %Y-%m-%dT%H:%M:%S.%NZ
</parse>
</source>
# we use kubernetes metadata plugin to add metadatas to the log
<filter kubernetes.**>
#type kubernetes_metadata
</filter>
<match kubernetes.var.log.containers.**kube-logging**.log>
#type null
</match>
<match kubernetes.var.log.containers.**kube-system**.log>
#type null
</match>
<match kubernetes.var.log.containers.**monitoring**.log>
#type null
</match>
<match kubernetes.var.log.containers.**infra**.log>
#type null
</match>
# we send the logs to Elasticsearch
<match kubernetes.**>
#type elasticsearch_dynamic
#id out_es
#log_level debug
include_tag_key true
host "#{ENV['FLUENT_ELASTICSEARCH_HOST']}"
port "#{ENV['FLUENT_ELASTICSEARCH_PORT']}"
scheme "#{ENV['FLUENT_ELASTICSEARCH_SCHEME'] || 'http'}"
reload_connections true
logstash_format true
logstash_prefix ${record['kubernetes']['pod_name']}
<buffer>
#type file
path /var/log/fluentd-buffers/kubernetes.system.buffer
flush_mode interval
retry_type exponential_backoff
flush_thread_count 2
flush_interval 5s
retry_forever true
retry_max_interval 30
chunk_limit_size 2M
queue_limit_length 32
overflow_action block
</buffer>
</match>
However, with my own fluent.conf it failed with the following error message
Error Message
2022-03-03 11:23:59 +0000 [debug]: #0 [out_es] 'host 192.xxx.xx.xxx' is tested built-in placeholder(s) but there is no valid placeholder(s). error: Parameter 'host: 192.xxx.xx.xxx' doesn't have tag placeholder
2022-03-03 11:23:59 +0000 [debug]: #0 [out_es] 'index_name fluentd' is tested built-in placeholder(s) but there is no valid placeholder(s). error: Parameter 'index_name: fluentd' doesn't have tag placeholder
2022-03-03 11:23:59 +0000 [debug]: #0 [out_es] 'template_name ' is tested built-in placeholder(s) but there is no valid placeholder(s). error: Parameter 'template_name: ' doesn't have tag placeholder
2022-03-03 11:23:59 +0000 [debug]: #0 [out_es] 'logstash_prefix index-%Y.%m.%d' is tested built-in placeholder(s) but there is no valid placeholder(s). error: Parameter 'logstash_prefix: index-%Y.%m.%d' has timestamp placeholders, but chunk key 'time' is not configured
2022-03-03 11:23:59 +0000 [debug]: #0 [out_es] 'logstash_prefix index-%Y.%m.%d' is tested built-in placeholder(s) but there is no valid placeholder(s). error: Parameter 'logstash_prefix: index-%Y.%m.%d' doesn't have tag placeholder
2022-03-03 11:23:59 +0000 [debug]: #0 [out_es] 'logstash_dateformat %Y.%m.%d' is tested built-in placeholder(s) but there is no valid placeholder(s). error: Parameter 'logstash_dateformat: %Y.%m.%d' has timestamp placeholders, but chunk key 'time' is not configured
2022-03-03 11:23:59 +0000 [debug]: #0 [out_es] 'logstash_dateformat %Y.%m.%d' is tested built-in placeholder(s) but there is no valid placeholder(s). error: Parameter 'logstash_dateformat: %Y.%m.%d' doesn't have tag placeholder
2022-03-03 11:23:59 +0000 [debug]: #0 [out_es] 'deflector_alias ' is tested built-in placeholder(s) but there is no valid placeholder(s). error: Parameter 'deflector_alias: ' doesn't have tag placeholder
2022-03-03 11:23:59 +0000 [debug]: #0 [out_es] 'application_name default' is tested built-in placeholder(s) but there is no valid placeholder(s). error: Parameter 'application_name: default' doesn't have tag placeholder
2022-03-03 11:23:59 +0000 [debug]: #0 [out_es] 'ilm_policy_id logstash-policy' is tested built-in placeholder(s) but there is no valid placeholder(s). error: Parameter 'ilm_policy_id: logstash-policy' doesn't have tag placeholder
2022-03-03 11:23:59 +0000 [debug]: #0 [out_es] Need substitution: false
I tried suggestions googling however I am not sure what's missing in the config file. Any help is highly appreciated