What support means with chatty device: at least one, or more devices are sending way too much (polling) events.
(It’s very odd they can’t see WHICH device(s) in the logs…)
This can only be fixed by increasing polling intervals (via the device settings), if present.
If not present, with Homey 2023 and newer, the only way to discover it, is to remove each zigbee device, one at a time, to find the chatty one(s): when zigbee mesh is quick and snappy again, you found it.
To re-add a “good” zigbee device, you can choose what’s less work or less time consuming:
just restore a recent backup,
or
add the device again, and fix the flows involved.
This neat script can be of great help. It can replace a device in many flows at once.
Hint:
Power metering devices can be very chatty
