Is C# compiler that smart or am I benchmarking wrong?

using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;

BenchmarkRunner.Run<AccessBenchmark>();

class Flat { public int Value { get; set; } }
class Nested { public Flat Flat { get; set; } }

public class AccessBenchmark {
    private const int N = 100000;
    private const int MaxValue = int.MaxValue / N;
    private readonly Random random = new();
    private readonly Flat[] flats;
    private readonly Nested[] nesteds;

    public AccessBenchmark() {
        flats = new Flat[N];
        nesteds = new Nested[N];
        for (var i = 0; i < N; i++) {
            flats[i] = new Flat { Value = random.Next(MaxValue) };
            nesteds[i] = new Nested { Flat = new Flat { Value = random.Next(MaxValue) } };
        }
    }

    [Benchmark]
    public int Flat() => flats.Sum(x => x.Value);

    [Benchmark]
    public int Nested() => nesteds.Sum(x => x.Flat.Value);
}

| Method | Mean     | Error   | StdDev  |
|------- |---------:|--------:|--------:|
| Flat   | 218.8 us | 2.96 us | 2.77 us |                                                                                                            
| Nested | 200.2 us | 3.89 us | 5.70 us |