C# - nullability warning disappears when commenting out *seemingly* unrelated code

Question

I've found some behaviour with the nullability analysis in a C# project that I don't understand, and I was hoping someone might be able to shed some light on it.

In short, I've got a nullability warning which I can't work out why it's appearing and, more confusingly, it disappears when I comment out some code that doesn't look like it should affect the nullability analysis.

It's probably just easier to show the code than try to describe it in more detail - an MRE is as follows...

ConsoleApp1.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net6.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

</Project>

Program.cs

static object? GetTask()
{
    return new object();
}

static void DoSomething()
{

    var plans = Enumerable.Empty<Plan>();

    var filtered = plans
        .Select(
            plan => new
            {
                Value = plan.Schedule
            }
        );

    var tasks = filtered.Select(
        anon => GetTask()
    );

}

DoSomething();

class Plan
{
    public object? Schedule
    {
        get;
        set;
    }
}

The code as-is gives a nullability warning:

CS8619 Nullability of reference types in value of type '<anonymous type: object Value>' doesn't match target type '<anonymous type: object? Value>'.

but if I comment out the var tasks = ... statement the nullability warning disappears...

It looks like the analyser is getting its knickers in a twist because it decides that the Value property of the anonymous type should be "not null" (i.e. <anonymous type: object Value>) but then proceeds to create an anonymous object with a nullable Value (i.e. <anonymous type: object? Value>.

It also seems to be related to the GetTasks method - if you replace anon => GetTask() with anon => null as object the nullability warning goes away as well:

I'm half-imagining this might be a bug in the nullability analyser, but is there a rational explanation that I just can't see?

For reference, versions are:

Microsoft Visual Studio Professional 2022 (64-bit) - Preview
Version 17.3.0 Preview 1.1

and

C:>dotnet --list-sdks
3.1.419 [C:\Program Files\dotnet\sdk]
5.0.200 [C:\Program Files\dotnet\sdk]
5.0.214 [C:\Program Files\dotnet\sdk]
6.0.203 [C:\Program Files\dotnet\sdk]
6.0.300 [C:\Program Files\dotnet\sdk]
7.0.100-preview.4.22252.9 [C:\Program Files\dotnet\sdk]

Update

Moving the code out of the DoSomething method also seems to remove the warning: