### Godot version

v4.0.beta14.official [28a24639c]

### System information

Windows 10, OpenGL

### Issue description

Vulkan and Mobile:
![Godot_v4 0-beta14_win64_kEcRNiMfNJ](https://user-images.githubusercontent.com/7782218/213967627-8e8755d9-2fe2-43b3-b197-f9f2840b7580.gif)

OpenGL:
![Godot_v4 0-beta14_win64_MQ233TZuPq](https://user-images.githubusercontent.com/7782218/213967651-ae463a6f-c867-4312-bdf1-525e1d7def01.gif)

At first I thought it was related to `set_buffer()`, but it turned out that `set_instance_*` also work incorrectly.
Probably the custom information is also set incorrectly, but I haven't checked it yet.

### Steps to reproduce

* Open MRP
* In the editor, select `MeshInstance3D` node and change the `Count` property
* -- or --
* Start the project and move the slider

You can also switch the renderer to Vulkan and compare.

### Minimal reproduction project

[set_buffer().zip](https://github.com/godotengine/godot/files/10476834/set_buffer.zip)

glBindBuffer(GL_ARRAY_BUFFER, 0);
	} else {
		
		ERR_FAIL_COND(p_buffer.size() != (multimesh->instances * (int)multimesh->stride_cache));
		const float *r = p_buffer.ptr();
		glBindBuffer(GL_ARRAY_BUFFER, multimesh->buffer);
		glBufferData(GL_ARRAY_BUFFER, p_buffer.size() * sizeof(float), r, GL_STATIC_DRAW);
		glBindBuffer(GL_ARRAY_BUFFER, 0);
	}
	multimesh->buffer_set = true;
	if (multimesh->data_cache.size() || multimesh->uses_colors || multimesh->uses_custom_data) {
		
		multimesh->data_cache = multimesh->data_cache;
		{
			
			uint32_t data_cache_dirty_region_count = (multimesh->instances - 1) / MULTIMESH_DIRTY_REGION_SIZE + 1;
			for (uint32_t i = 0; i < data_cache_dirty_region_count; i++) {
				multimesh->data_cache_dirty_regions[i] = false;
			}
			multimesh->data_cache_used_dirty_regions = 0;
		}
		_multimesh_mark_all_dirty(multimesh, false, true); 
	} else if (multimesh->mesh.is_valid()) {
		
		const float *data = p_buffer.ptr();
		_multimesh_re_create_aabb(multimesh, data, multimesh->instances);
		multimesh->dependency.changed_notify(Dependency::DEPENDENCY_CHANGED_AABB);
	}
}
Vector<float> MeshStorage::multimesh_get_buffer(RID p_multimesh) const {