Zigbee network opens for joining by itself

I have a slae.sh zigbee stick CC2652 with a blue LED. I’m using it with ZHA. The LED goes on when I add new devices to the network. But sometimes it goes on when I don’t do anything with HA. Is this some kind of maintenance acitivity of HA, maybe for scanning the network architecture?

Which stick and which zigbee integration do you use?

Sorry I forgot to write! Its a TI CC2652 (ZNP) with ZHA.