### Godot version

4.1.1.stable, 4.2.dev (2282fc5de)

### System information

Arch Linux - X11 - GLES3 (Compatibility) - NVIDIA GeForce RTX 3060 Ti (nvidia; 535.104.05) - 13th Gen Intel(R) Core(TM) i5-13400F (16 Threads)

### Issue description

When using Compatibility renderer, adjusting the Alpha component of clear color affects 2D editor content.

This does not happen when using Forward+ or Mobile renderer. Does not affect 3D editor and the running game.


https://github.com/godotengine/godot/assets/372476/e398522e-590a-4832-959f-ea8ba8e71c5d



### Steps to reproduce

1. Create a project using Compatibility renderer.
2. Adjust the clear color's alpha component in Project Settings.

### Minimal reproduction project

N/A
state.canvas_instance_batches[state.current_batch_index].instance_count++;
	r_index++;
	if (r_index + state.last_item_index >= data.max_instances_per_buffer) {
		
		
		glBindBuffer(GL_ARRAY_BUFFER, state.canvas_instance_data_buffers[state.current_data_buffer_index].instance_buffers[state.current_instance_buffer_index]);
#ifdef WEB_ENABLED
		glBufferSubData(GL_ARRAY_BUFFER, state.last_item_index * sizeof(InstanceData), sizeof(InstanceData) * r_index, state.instance_data_array);
#else
		
		void *buffer = glMapBufferRange(GL_ARRAY_BUFFER, state.last_item_index * sizeof(InstanceData), r_index * sizeof(InstanceData), GL_MAP_WRITE_BIT | GL_MAP_UNSYNCHRONIZED_BIT);
		memcpy(buffer, state.instance_data_array, r_index * sizeof(InstanceData));
		glUnmapBuffer(GL_ARRAY_BUFFER);
#endif
		_allocate_instance_buffer();
		r_index = 0;
		state.last_item_index = 0;
		r_batch_broken = false; 
		_new_batch(r_batch_broken);
		state.canvas_instance_batches[state.current_batch_index].start = 0;
	}
}
void RasterizerCanvasGLES3::_new_batch(bool &r_batch_broken) {