Now I found that after some time ConBee disappears from the host system:
[Sun Nov 20 20:40:04 2022] usb 1-5: usbfs: process 1768 (qemu-system-x86) did not claim interface 1 before use
[Sun Nov 20 20:40:04 2022] usb 1-5: usbfs: process 1768 (qemu-system-x86) did not claim interface 1 before use
[Sun Nov 20 20:40:04 2022] usb 1-5: usbfs: process 1768 (qemu-system-x86) did not claim interface 1 before use
[Sun Nov 20 20:40:04 2022] usb 1-5: usbfs: process 1768 (qemu-system-x86) did not claim interface 1 before use
[Sun Nov 20 20:40:04 2022] usb 1-5: usbfs: process 1768 (qemu-system-x86) did not claim interface 1 before use
[Sun Nov 20 20:40:04 2022] usb 1-5: USB disconnect, device number 2
[Sun Nov 20 20:40:04 2022] usb 1-5: new full-speed USB device number 4 using xhci_hcd
[Sun Nov 20 20:40:04 2022] usb 1-5: New USB device found, idVendor=1cf1, idProduct=0030, bcdDevice= 1.00
[Sun Nov 20 20:40:04 2022] usb 1-5: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[Sun Nov 20 20:40:04 2022] usb 1-5: Product: ConBee II
[Sun Nov 20 20:40:04 2022] usb 1-5: Manufacturer: dresden elektronik ingenieurtechnik GmbH
[Sun Nov 20 20:40:04 2022] usb 1-5: SerialNumber: DE2290983
[Sun Nov 20 20:40:04 2022] cdc_acm 1-5:1.0: ttyACM0: USB ACM device
[Sun Nov 20 20:40:08 2022] usb 1-5: USB disconnect, device number 4
[Sun Nov 20 20:40:08 2022] usb 1-5: new full-speed USB device number 5 using xhci_hcd
[Sun Nov 20 20:40:08 2022] usb 1-5: New USB device found, idVendor=1cf1, idProduct=0030, bcdDevice= 1.00
[Sun Nov 20 20:40:08 2022] usb 1-5: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[Sun Nov 20 20:40:08 2022] usb 1-5: Product: ConBee II
[Sun Nov 20 20:40:08 2022] usb 1-5: Manufacturer: dresden elektronik ingenieurtechnik GmbH
[Sun Nov 20 20:40:08 2022] usb 1-5: SerialNumber: DE2290983
[Sun Nov 20 20:40:08 2022] cdc_acm 1-5:1.0: ttyACM0: USB ACM device