Had the same issue. I got advice in the forum that if using USB manager plugin (which I do use), you can now change type of passing the device as serial mode.
https://forums.unraid.net/topic/100511-plugin-usb_manager/page/9/#comment-1147207
I changed that for my conbee stick, shut down VM, started it again. Then just changed path for device in Z2M from /dev/serial/by-id/conbeeXYZ to /dev/serial/by-id/qemuXYZ and that was it. All of my zigbee network continued to work.
Upgraded now to 6.10.3 without any issues.
