Sending proper mqtt commands receive switch status


I just can’t seem to get my mqtt lamp switch configuration right so I need some help here.
I have installed the following switch:

Pairing using zigbee2mqtt is working and Mosquitto shows the switch topic.

My switch configuration in openhab 3 is:

UID: mqtt:topic:543765dc0b:ce0e4d8e86
label: Deckenbeleuchtung
thingTypeUID: mqtt:topic
  payloadNotAvailable: offline
  availabilityTopic: zigbee2mqtt/deckenlampe_flur/availability
  payloadAvailable: online
bridgeUID: mqtt:broker:543765dc0b
location: Flur
  - id: switch
    channelTypeUID: mqtt:switch
    label: lamp
    description: ""
      commandTopic: zigbee2mqtt/deckenlampe_flur/set
      retained: false
      qos: 1
      stateTopic: zigbee2mqtt/deckenlampe_flur/state

When I click the switch in openhab, the state changes and the switch is working but 2 problems still persist:

  1. When clicking the switch in openhab, not only the state of the root JSON path changes but a second set topic appears.

  2. When I trigger the switch using the existing button on the wall, the state changes only in the root json pat but the other set stays the same - also Openhab doesn’t recognize the new state. Bildschirmfoto 2022-07-25 um 14.33.41

I just can’t figure out my mistake, even after searching everywhere on the forum or google.