Check that do not have any USB 3.0 devices/hubs/cables close as USB 3.0 are infamously known to cause interference for all 2.4GHz devices, especially for Zigbee but also for Bluetooth devices and Wi-Fi adapters if located too close to USB 3.0 devices/hubs/cables). Read:
https://www.usb.org/sites/default/files/327216.pdf
https://eshop.macsales.com/blog/15990-shielding-resolves-usb-3-0-conflict-with-bluetooth/
https://www.unit3compliance.co.uk/2-4ghz-intra-system-or-self-platform-interference-demonstration/
https://www.rshtech.com/blog/how-to-avoid-the-usb30-and-24-ghz-devices-interference-2
Someone even looks to have created a whole website dedicated to Bluetooth + USB 3 issues here:
https://www.bluetoothandusb3.com/
Zigbee should not cause interference problems for Bluetooth, but sometimes the reverse can happen, though it is much more common that Wi-Fi devices will cause interference problems for both Bluetooth and Zigbee. See:
https://www.home-assistant.io/integrations/bluetooth/#bluetooth-interference-with-other-devices
and
Also recommend reading and try following this guide which has other tips for Zigbee interference avoidance of which some could also be applicable to Bluetooth as well → Zigbee networks: how to guide for avoiding interference and optimize for getting better range + coverage