I u have a running MySQL Server and monitor it with zabbix and the official Mysql Template, and restart the mysql server the trigger MySQL: Buffer pool utilization is too low will fire, but it's quite normal that after a restart buffers are not full, it would be great to have this related with the uptime.. eg the server is running for more than 6h and the buffer isn't full, something like:

max(/MySQL by Zabbix agent 2/mysql.buffer_pool_utilization,5m)<{$MYSQL.BUFF_UTIL.MIN.WARN} and last(/MySQL by Zabbix agent 2/mysql.uptime)>6h

make much more sense