Errors of custom resources in C# for Godot

### Tested versions

4.4.stable.mono

### System information

Godot v4.4.stable.mono - Windows 11 (build 26100) - Multi-window, 2 monitors - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 3060 Ti (NVIDIA; 32.0.15.6109) - 13th Gen Intel(R) Core(TM) i5-13600K (20 threads)

### Issue description

```
using Godot;
using System;

[GlobalClass]public partial class CResource : Resource
{
private Vector2 _position = new(40,20);
[Export]public Vector2 Position
{
get => _position;
set => _position = value;
}
}
```

In this code, I set a variable named _position, and this variable can be modified freely.
To verify my data, I created the following code.

```
using Godot;

public partial class C : Node
{
public static CResource CResource1 = GD.Load("uid://jycnevj23t5e");
public static CResource CResource2 = GD.Load("uid://dqq0kpcwbrrwj");
public override void _Ready()
{
GD.Print("You can modify this part.");
GD.Print("My CResource1 is (40,20)");
GD.Print("My CResource1 is (42,42)");
GD.Print(CResource1.Position);
GD.Print(CResource2.Position);
}
}

```

When I modify it, the editor displays normally, but the output value is incorrect.
After restarting Godot, the output value in the editor becomes the printed value.
Currently, I have only encountered this situation in the resources.

### Steps to reproduce

Reset the resource data, then modify _position and run to get the output.

```
[GlobalClass]public partial class CResource : Resource
{
private Vector2 _position = new(40,20);
[Export]public Vector2 Position
{
get => _position;
set => _position = value;
}
}
```

Restarting the project will cause the bug to appear to be normal.
In my tests, the problem does not occur in GDScript.

### Minimal reproduction project (MRP)

[C.zip](https://github.com/user-attachments/files/19333667/C.zip)

Start by running the attached C.zip minimal reproduction with Godot 4.4.stable.mono and compare the editor values with the printed runtime values before and after restarting. Trace the C# custom Resource and exported-property handling implicated by the reproduction. Done means the saved resource values and runtime output agree without requiring a restart.

Written by the indexing model from the issue text.