If I understand correctly when running a node on TOR, DNS seeders are not utilized and it defaults to the harcoded list of .onion addresses.~
AFAIK, the node won't fetch any DNS seed only if you set up a config to disable it. Even if the node is running over Tor, it still fetches the DNS seeders, but the Tor exit nodes will resolve the DNS for the Bitcoin node.
I have what is the difference between onion and not_publicly_routable in the network fields ?
Onion means, the in/outbound connection is using the Tor network. The other one may come from a local P2P connection, as an example, if you are running Electrs, the electrs connection will result
not_publicly_routable. Other than that, it just means that the connection/network isn't routable over the internet.