My turn, a BILRESA scroll named “BILRESA bad” went offline, but not only that.
At 7:20 CET (6:20 UTC) it generated four button pressed events on its own without user intervention, I don’t know if it was the button sending them or SmartThings repeating them. I don’t remember pressing it and if I did it was not four times, that’s for sure.
Now the button is bricked, the selector of the bottom won’t cycle the lights, presses do nothing. It’s not the first time though, so may as well be a bug in IKEA firmware.
Dumped the logs.
Edit: I finally factory reset the button and is working again. I believe it was actually connected to the Thread network because I could see it in mDNS records, I guess the problem was the Matter session and that’s why it appeared as offline.