### 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)

attributes_stride += 2 * sizeof(float);
				attribs[i].normalized = GL_FALSE;
			} break;
			case RS::ARRAY_TEX_UV2: {
				attribs[i].offset = attributes_stride;
				attribs[i].size = 2;
				attribs[i].type = GL_FLOAT;
				attributes_stride += 2 * sizeof(float);
				attribs[i].normalized = GL_FALSE;
			} break;
			case RS::ARRAY_CUSTOM0:
			case RS::ARRAY_CUSTOM1:
			case RS::ARRAY_CUSTOM2:
			case RS::ARRAY_CUSTOM3: {
				attribs[i].offset = attributes_stride;
				int idx = i - RS::ARRAY_CUSTOM0;
				uint32_t fmt_shift[RS::ARRAY_CUSTOM_COUNT] = { RS::ARRAY_FORMAT_CUSTOM0_SHIFT, RS::ARRAY_FORMAT_CUSTOM1_SHIFT, RS::ARRAY_FORMAT_CUSTOM2_SHIFT, RS::ARRAY_FORMAT_CUSTOM3_SHIFT };
				uint32_t fmt = (s->format >> fmt_shift[idx]) & RS::ARRAY_FORMAT_CUSTOM_MASK;
				uint32_t fmtsize[RS::ARRAY_CUSTOM_MAX] = { 4, 4, 4, 8, 4, 8, 12, 16 };
				GLenum gl_type[RS::ARRAY_CUSTOM_MAX] = { GL_UNSIGNED_BYTE, GL_BYTE, GL_HALF_FLOAT, GL_HALF_FLOAT, GL_FLOAT, GL_FLOAT, GL_FLOAT, GL_FLOAT };
				GLboolean norm[RS::ARRAY_CUSTOM_MAX] = { GL_TRUE, GL_TRUE, GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE };
				attribs[i].type = gl_type[fmt];
				attributes_stride += fmtsize[fmt];
				attribs[i].size = fmtsize[fmt] / sizeof(float);
				attribs[i].normalized = norm[fmt];
			} break;
			case RS::ARRAY_BONES: {
				attribs[i].offset = skin_stride;
				attribs[i].size = 4;
				attribs[i].type = GL_UNSIGNED_SHORT;