Possible issue in C# Garbage Collection behavior

### Tested versions

- Reproducible in 4.2.2-stable and 4.3-beta2. See linked issue for more info

### System information

Godot v4.2.2.stable.mono - Windows 10.0.19045 - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 2070 SUPER (NVIDIA; 31.0.15.5212) - AMD Ryzen 9 3900X 12-Core Processor (24 Threads)

### Issue description

To keep it short, the full issue is actually described here
https://github.com/TokisanGames/Terrain3D/issues/393
and there is a possibility there is an underlying problem in how the GC is handling resources and gdextension data. I would love it if someone from the csharp team could give it a look and throw some ideas around.

### Steps to reproduce

Please see linked issue.

### Minimal reproduction project (MRP)

Please see linked issue.

Start with the linked Terrain3D issue #393, since the reproduction steps and minimal project are there. Investigate the reported interaction between C# garbage collection, resources, and GDExtension data in Godot 4.2.2/4.3-beta2. Done means establishing whether Godot has a reproducible underlying bug and documenting a confirmed cause or next diagnostic step.

Written by the indexing model from the issue text.