How can i add a timezone to my Timestamp Logentry

I have several log files with different timestamp formats. A log file like this:

[2021/12/22 09:52:44] [error] **********
[2021/12/22 09:52:44] [error] **********
[2021/12/22 09:52:44] [ warn] *********

In the other file like this:
[2021-12-22 10:15:00.055 +0100CET] WARN *******
[2021-12-22 10:15:00.055 +0100CET] WARN *******
[2021-12-22 10:15:00.057 +0100CET] WARN *******
[2021-12-22 10:15:00.058 +0100CET] WARN *******

The timestampe entrys are with and with out timezone specification.

The logentry with the timezone in the timestamp are displayd correctly in Kibana.

But the logentry without the timezone are displyed one hour off

My Output Conf in Fluentd is the following:
<match *>
@type elasticsearch
time_key_exclude_timestamp true
logstash_format true
logstash_prefix ${tag}
@type file
path /srv/spool/td-agent-buffer
flush_mode interval
flush_thread_count 8
flush_thread_interval 1.0
flush_interval 5s
chunk_limit_size 45M
chunk_full_threshold 0.95
queued_chunks_limit_size 8
total_limit_size 64GB
overflow_action throw_exception
retry_forever true
request_timeout 20s
slow_flush_log_threshold 40.0
host *******
port ******
scheme https
user *****
password ****
ca_file /etc/td-agent/elasticsearch-ca.pem

How can i add a Timezone in Fluentd to my Logentrys, so that there are also displayd correctly in Kibana?