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.
{
public:
    typedef std::function<void(TorControlConnection&)> ConnectionCB;
    typedef std::function<void(TorControlConnection &,const TorControlReply &)> ReplyHandlerCB;
    /** Create a new TorControlConnection.
     */
    explicit TorControlConnection(struct event_base *base);
    ~TorControlConnection();
    /**
     * Connect to a Tor control port.
     * target is address of the form host:port.
     * connected is the handler that is called when connection is successfully established.
     * disconnected is a handler that is called when the connection is broken.
     * Return true on success.
     */
    bool Connect(const std::string &target, const ConnectionCB& connected, const ConnectionCB& disconnected);
    /**
     * Disconnect from Tor control port.
     */
    void Disconnect();
    /** Send a command, register a handler for the reply.
     * A trailing CRLF is automatically added.
     * Return true on success.
     */