OpenWrt 22.03 detailed bandwith monitoring with NFTtables + collectd

I was using this iptmon script + collectd + grafana to monitor individual
clients bandwith usage.

that is not compatible with NFTtables in latest releases.
Is there something similar to retrieve (and remotely send) bandwidth stats for individual clients?

Try to see if this help: Show usage per IP

Install Nlbwmon and export its statistics to collectd with lua plugin:
With this plugin you can get the same per host traffic statistics as with Iptmon (after small script change statistics are exactly the same)

By exporting to Grafana you will get much nicer pictures: