Forgot about zigbee2mqtt running with permit_join true and 2 devices joined my zigbee network / 2021-07-03

I sort of forgot I had zigbee2mqtt running since 18 June and the network enhanced itself with two devices: a 'lidl smart plug' and a 'power supply/relay/dimmer'. The Lidl Silvercrest smart plug (EU, CH, FR, BS, DK) (HG06337) left the network by itself but the Busch-Jaeger Zigbee Light Link power supply/relay/dimmer (6735/6736/6737) was actively reporting and I was able to switch the light on and off.

After resetting it to the state I found it in I tried to remove it from the network (by sending a 'remove' message to zigbee2mqtt) but it came back right away. So I stopped zigbee2mqtt, set permit_join to false and restarted it. After that I gave the 'remove' command again and that worked and it hasn't come back.

Log from zigbee2mqtt with the device id removed:

Zigbee2MQTT:info  2021-07-03 15:59:04: MQTT publish: topic 'zigbee2mqtt/0xd85def11a1004f69', payload '{"brightness_relay":254,"linkquality":33,"state_relay":"OFF"}'
Zigbee2MQTT:info  2021-07-03 15:59:08: Removing '0x****************'
Zigbee2MQTT:info  2021-07-03 15:59:08: Successfully removed 0x****************
Zigbee2MQTT:info  2021-07-03 15:59:08: MQTT publish: topic 'zigbee2mqtt/bridge/log', payload '{"message":"0x****************","type":"device_removed"}'
Zigbee2MQTT:warn  2021-07-03 15:59:08: Device '0x****************' left the network
Zigbee2MQTT:info  2021-07-03 15:59:08: MQTT publish: topic 'zigbee2mqtt/bridge/event', payload '{"data":{"ieee_address":"0x****************"},"type":"device_leave"}'
Zigbee2MQTT:info  2021-07-03 15:59:08: MQTT publish: topic 'zigbee2mqtt/bridge/log', payload '{"message":"left_network","meta":{"friendly_name":"0x****************"},"type":"device_removed"}'
Zigbee2MQTT:warn  2021-07-03 15:59:08: Device '0x****************' left the network
Zigbee2MQTT:info  2021-07-03 15:59:08: MQTT publish: topic 'zigbee2mqtt/bridge/event', payload '{"data":{"ieee_address":"0x****************"},"type":"device_leave"}'
Zigbee2MQTT:info  2021-07-03 15:59:08: MQTT publish: topic 'zigbee2mqtt/bridge/log', payload '{"message":"left_network","meta":{"friendly_name":"0x****************"},"type":"device_removed"}'

Sorry to whoever in the neighbourhood wasn't able to get their new lightswitch/dimmer working with their own hub. It should work now.

I checked the documentation and it's perfectly possible to tell zigbee2mqtt to allow/deny joins (even for a set time) via a message delivered via mqtt: MQTT topics and message structure: zigbee2mqtt/bridge/request/permit_join. I will leave the fixed configuration to joins disabled and will allow a join by hand when there is an actual device to join.