https-dns-proxy modifies the dnsmasq config to route DNS requests through it, including the router itself. When sysupgrade runs, the https-dns-proxy package (and all others, of course) is removed, but when the new build tries to reinstall https-dns-proxy, it can't because all DNS requests fail...a chicken-and-egg problem.
Is there a clean solution for this, short of adding Google DNS or similar temporarily to dnsmasq to allow bare DNS requests to work? How are others handling this?
as frollic said. Set your router DNS to your ISP or Google or Cloudflare DNS. Your router does not need adblocking or encrypted DNS. This means it will always be able to update NTP or do opkg updates even if your https-dns-proxy is broken. (I also set it that way for AdGuardHome in my thread).
Imagebuilder but i believe you'd still have to setup the config files?