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.
int script_threads = args.GetArg("-par", DEFAULT_SCRIPTCHECK_THREADS);
    if (script_threads <= 0) {
        
        
        script_threads += GetNumCores();
    }
    
    script_threads = std::max(script_threads - 1, 0);
    
    script_threads = std::min(script_threads, MAX_SCRIPTCHECK_THREADS);
    LogPrintf("Script verification uses %d additional threads\n", script_threads);
    if (script_threads >= 1) {
        g_parallel_script_checks = true;
        for (int i = 0; i < script_threads; ++i) {
            threadGroup.create_thread([i]() { return ThreadScriptCheck(i); });
        }
    }
    assert(!node.scheduler);
    node.scheduler = MakeUnique<CScheduler>();
    
    threadGroup.create_thread([&] { TraceThread("scheduler", [&] { node.scheduler->serviceQueue(); }); });
    
    node.scheduler->scheduleEvery([]{
        RandAddPeriodic();
    }, std::chrono::minutes{1});
    GetMainSignals().RegisterBackgroundSignalScheduler(*node.scheduler);
    /* Register RPC commands regardless of -server setting so they will be
     * available in the GUI RPC console even if external calls are disabled.
     */
    RegisterAllCoreRPCCommands(tableRPC);