https://github.com/bitcoin/bitcoin/blob/d72758c3f6c34cd835f5de3efc230964f3b1ea56/src/torcontrol.cpp#L539

If a user is running Tor proxy outside localhost (perhaps on other host inside LAN or in containerised environment) , the automatic creation of onion services ends up creating an onion service listening to hardcored 127.0.0.1 address on the Tor proxy's host instead of the private address of the bitcoind – effectively running an empty onion service listening the Tor proxy's localhost.
#ifndef BITCOIN_CHAINPARAMSBASE_H
#define BITCOIN_CHAINPARAMSBASE_H
#include <memory>
#include <string>
class ArgsManager;
/**
 * CBaseChainParams defines the base parameters (shared between bitcoin-cli and bitcoind)
 * of a given instance of the Bitcoin system.
 */
class CBaseChainParams
{
public:
    
    
    static const std::string MAIN;
    static const std::string TESTNET;
    static const std::string SIGNET;
    static const std::string REGTEST;
    
    const std::string& DataDir() const { return strDataDir; }