Source IP: x.x.x.x, Source Port: x, Destination IP: x.x.x.x
Layer 7 firewall rule Deny
In a recent upgrade on Threat Intelligence and Content filtering. Cisco Meraki moved on to Talos Threat Intelligence from Brightcloud Threat Intelligence. This upgrade has provided enhanced security to Meraki Users.
However you may see limited information about the NBAR Details under the event logs.
Below thread reveals the details of NBAR ID.
Mapping Layer 7 Firewall Rules to NBAR IDs
Network-Based Application Recognition (NBAR) Integration
Network-Based Application Recognition (NBAR) integration with MR access points