I noticed Zigbee stuff stopped working. I have a CC2531 plugged into RPi4 USB port. It was set to use /dev/ttyACM1, yet SOMEHOW, the plug (that I haven´ t touched in like a year) became /dev/ttyACM0. Upon changing this in the zigbee2mqtt config, all is working again. I repeat, I didn´t touch either the physical Pi NOR the Z2M config at all.
Super weird, any further explanations?