Not OP, but in my case, most of my VLANs can’t perform DNS requests to WAN. Only the pi.hole server is able to do that (and other devices in the DMZ).
Reasoning: appliances like Chromecast/Apple TV/whatever will often ignore DHCP DNS settings if it doesn’t resolve, and they’ll reach out to 8.8.8.8/8.8.4.4 directly.
