Logstash (TypeError) no implicit conversion of Hash into String

For a couple of days, logstash stops ingesting logs (while the service is up and running). The error thrown on the logs is shown below:

2024-07-22 12:10:36,103 pool-84-thread-1 ERROR An exception occurred processing Appender plain_rolling org.jruby.exceptions.TypeError: (TypeError) no implicit conversion of Hash into String

This is the command defined on .service file:

ExecStart=/usr/share/logstash/bin/logstash "--path.settings" "/etc/logstash"

I need help to identify what is causing the issue?