Whonix ws VM no DNS when NetVM is not sys-whonix

I was configuring a VPN-over-Tor setup in Qubes 4.2, but encountered a problem.
If I set a ProxyVM as the NetVM of my Whonix ws VM (anon-whonix), whether the ProxyVM is a VPN VM, or just a plain “provides network” Debian-based VM between anon-whonix and sys-whonix, DNS queries from anon-whonix will always fail.
For VPN VM, I tried “Set up a ProxyVM as a VPN gateway using iptables and CLI scripts” and Qubes-vpn-support by tasket, both with changes relevant to nftables, but the results were the same.
I found that changing the name server IP in /etc/resolv.conf in anon-whonix to, instead of current NetVM’s IP (Whonix default), does solve the problem, but I don’t know if it’s a suggested way.
Any help would be appreciated.

[irrelevant comment retracted]