Interference, as well Zigbee channel choice, can still be a problem, but you also need to understand that Zigbee compatibility between different manufacturers/brands is not always that great which is why I personally recommend getting a few dedicated “know good” Zigbee Router devices. Read and follow:
A tip is to buy a few known good dedicated Zigbee Router products and place them strategically as Zigbee repeaters. Personally, I suggest buying and adding at least three such devices to your network.
For example, the “IKEA Tradfri Signal Repeater” works very well out-of-the-box, while a more powerful alternative is to make yourself some semi-DIY variant by flashing the correct Zigbee Router firmware to Zigbee Coordinator USB dongles and then using them as stand-alone Zigbee Signal Repeater devices in USB-chargers for power, like for example the Sonoff ZBDongle-E (EFR32MG21 based) or the Sonoff ZBDongle-P (CC2652P) work great as dedicated stand-alone Zigbee Signal Repeaters with recommended firmware.
Here are also some ZHA integration documentation sections directly and indirectly related to this topic:
https://www.home-assistant.io/integrations/zha#defining-zigbee-channel-to-use
https://www.home-assistant.io/integrations/zha#knowing-which-devices-are-supported
https://www.home-assistant.io/integrations/zha#zha-exception-and-deviation-handling