Sophos Central Firewall Manager (CFM) maintenance scheduled for Wednesday, July 8th starting at 06:30 GMT. Expected time to complete is 5 hours. Partners will be unable to access CFM during this period.

Rename of firewall name is removed from 2020.08 onwards

... and as the changelog says, Admin can change the firewall hostname from XG and same hostname it will reflect in Firewall Groups page UI

But even I renamed a couple of firewalls, they still appear with the serial number.