Well “they” is neither deCONZ nor Home Assistant, looking at Upgrade deConz to v2.28.1 by jannickfahlbusch · Pull Request #3708 · home-assistant/addons · GitHub (with the first discovery of this UI issue at Upgrade deConz to v2.28.1 by jannickfahlbusch · Pull Request #3708 · home-assistant/addons · GitHub) it looks like a voluntary user finally provided an update for the HA deCONZ addon - after months of staying behind latest deCONZ stable releases.
Some information bout this window manager change at Upgrade deConz to v2.28.1 by jannickfahlbusch · Pull Request #3708 · home-assistant/addons · GitHub.
It all comes back to the never-ending core issue: nobody is REALLY taking care about deCONZ (specifically the addon) in Home Assistant. HA devs don’t understand the deCONZ mechanics, deCONZ team has no interest and/or no human resources to support the addon (yes, they still accept to not have full or ANY control about their product in the most important home automation system on this planet).
I put in so much energy in bringing up discussions about and raising awareness for this bad situation so so SO many times especially this year. Last time the mod even banned me on Discord - not being rude, just fingerpointing at this situation. Therefore I’m pretty much done with that “look, another result of the unmaintained deCONZ HA addon status” issue. Users need to accept that unacceptable situation - or migrate away from deCONZ software. This issue/topic and the now two months of wasted time seem to just act as another proof for this.