According to Arista, if you see only input discards and no other counter incrementing, it is likely the issue is due to valid frames being input on that port, then having to be processed by the CPU (software processing) and causing congestion and then being dropped due to lack of resources or limitations on CPU processing.
The verbose output you list shows no match in any document I can find, is there a typo? It may mean simply that the processor dropped the packet due to it taking too long to process compared to some kind of control plane protection policy.
The first step I would take to discover the cause of the problem would be to mirror traffic on that port to a packet capture on a computer and see if there is any traffic that should obviously not be there. Improper VLAN tagging, broadcasts or other traffic might be flooded to the CPU and cause discards. There are many other types of traffic that might cause issues but it depends on the hardware and software configuration in use.