Clarification on the use of Upstream DNS Servers

[logicito]

I have setup AdGuard Home within a VM running Alpine Linux in Proxmox, its IP is 10.10.10.3, the router is OpenWrt also running as a VM within Proxmox, its IP is 10.10.10.1, within the AdGuard Home's VM, Alpine has configured the default gateway and DNS server IPs are 10.10.10.1.

I have configured as Upstream servers in AdGuard Home:

https://dns.cloudflare.com/dns-query
https://dns.quad9.net/dns-query

AdGuard Home is listening on all ports, in the AdGuardHome.yaml file I have:

dns:
  bind_hosts:
    - 0.0.0.0
  port: 53

When I check the AdGuard Home statistics, I see the router 10.10.10.1 as an upstream DNS resolver (attached print screen), why is this? I am sure I have something miss configured in AdGuard Home, Alpine or the OpenWrt router, any ideas or feedback will be appreciated, thank you