Weird Deconz bug with one entity toggling on/off another- not sure what's causing it

I’m experiencing a weird bug with a couple of my entities and i’m not sure what’s causing it.

I have two entities:

light.upstairs_landing (just a standard white ikea bulb), and

climate.upstairs_heater (which is made up of an aqara temperature sensor and an ikea plug using the generic_thermostat platform)

for some strange reason, when i turn off light.upstairs_landing (whether using the HA app or via an automation) the heater switch entity also turns off. and vice versa when turning it on. same goes if i turn on/off the heater, it also triggers the light.

I don’t think this is related to the generic_thermostat integration as it appears to also happen also when i just switch on/off the ikea plug on its own.

none of the entities are grouped together otherwise - they are added to HA using deconz.

Has anyone experienced anything similar? I’m scratching my head trying to figure out what’s causing this…

I experienced some weird behavior with a broken hue bulb. The zigbee transciever seems to be broken.
Can you exclude that?
Maybe recoupling helps?