How many threads does the uno-platform support for WASM (webassembly) projects?

I am trying to determine if the uno-platform will work for a specific project that I want to deploy as a WebAssembly app.

I've played around with Uno and have configured the newly available threading support using:

 <MonoWasmRuntimeConfiguration>threads-release</MonoWasmRuntimeConfiguration>

As I understand it, threading support is only available in Chrome and Edge at this time...but that is ok for my needs.

I've created a simple button that should spin up 10 worker threads like so:

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            for (int i = 0; i < 10; i++)
            {
                var t = new Thread(() => DoWork());
                t.Start();

            }

        }

        private void DoWork()
        {
            for (int n = 0; n < 10000; n++)
            {
                Console.WriteLine($"Task {Thread.CurrentThread.ManagedThreadId} running {n}");
            }
        }

This code is the only thing added to the default "hello world" WASM project from the uno-platform templates.

When looking at the output, I can see that 2 threads are working as expected and interweaving results. (prior to the <MonoWasmRuntimeConfiguration>threads-release</MonoWasmRuntimeConfiguration> the output would be synchronous for a single "thread" and then synchronous for the next "thread")

Task 3 running 9987

Task 2 running 9843

Task 3 running 9988

At the completion of both threads, the follow warning is logged in the browser console.

PThread 70424616 is attempting to join to itself!
__emscripten_do_pthread_join @ dotnet.js:1
_pthread_join @ dotnet.js:1
mono_native_thread_join @ 00806cba:0x70078
threads_native_thread_join_lock @ 00806cba:0xbfd98
mono_threads_join_threads @ 00806cba:0x6aefe
mono_runtime_do_background_work @ 00806cba:0xdb520
mono_background_exec @ 00806cba:0xf89c5
Module._mono_background_exec @ dotnet.js:1
pump_message @ dotnet.js:1
setTimeout (async)
_schedule_background_exec @ dotnet.js:1
mono_threads_schedule_background_job @ 00806cba:0x1612c
mono_threads_add_joinable_runtime_thread @ 00806cba:0xd8aa4
sgen_client_thread_detach_with_lock @ 00806cba:0xc67bd
thread_detach_with_lock @ 00806cba:0xc0142
unregister_thread @ 00806cba:0x5e469
mono_thread_info_detach @ 00806cba:0xd98c6
mono_thread_info_exit @ 00806cba:0x49724
start_wrapper @ 00806cba:0xc1206
dynCall_ii @ 00806cba:0x11d3d7
Module.dynCall_ii @ dotnet.js:1
onmessage @ dotnet.worker.js:1

Two questions arise which I can't find documentation about.

1. Why only 2 threads? (on both Chrome and Edge) Is this a browser limitation? A setting in Uno-platform?
2. Why do the remaining 8 threads not get started? They are essentially lost and none of the work gets performed. Is this a bug in the uno-platform? Mono? emscripten possibly?

I know threading is still experimental, but I am curious if there is a known limitation that I am hitting?