ThreadsGrowth.cs

using System.Collections.Concurrent;
using System.Diagnostics;
using System.Threading.Channels;

var lockObject = new object();
var blockingCollection = new BlockingCollection<int>(10);
var channel = Channel.CreateBounded<int>(new BoundedChannelOptions(10) {SingleReader = true});

var cts = new CancellationTokenSource();
cts.CancelAfter(30000);

while (!cts.IsCancellationRequested)
{
    Task.Run(() =>
    {
        //blockingCollection.Add(0);  //Result - 52 threads
        //channel.Writer.WriteAsync(0).AsTask().GetAwaiter().GetResult(); // Result - 147 threads
        //lock (lockObject) { channel.Writer.WriteAsync(0).AsTask().GetAwaiter().GetResult(); } //Result - 56 threads
        //var j = 1 + 1; // Result - 15 threads
    });
    Console.WriteLine(Process.GetCurrentProcess().Threads.Count);
}