In the Frontends documentation (https://www.zabbix.com/documentation/3.2/manual/web_interface/frontend_sections/monitoring/problems) there is no any information about the purpose of "Info" field. The same for 3.4 documentation.

As far as I know that the field is for informing the user If a problem was closed by global correlation or manually by acknowledgement.

Regards,
Aleksejs!