mqtt-react-hooks declares the dependency for mqtt as "^4.2.8", which at the time of writing will install mqtt 4.3.5 on a fresh installation. This results in published messages not being deleted from the outgoing mqtt.Store with qos 1, even if PUBACK is received. Forcing the dependency to mqtt 4.2.8 resolves the problem.
mqtt-react-hooks declares the dependency for mqtt as "^4.2.8", which at the time of writing will install mqtt 4.3.5 on a fresh installation. This results in published messages not being deleted from the outgoing mqtt.Store with qos 1, even if PUBACK is received. Forcing the dependency to mqtt 4.2.8 resolves the problem.