### Godot version

v4.0.beta12.official [3c9bf4bc2]

### System information

Windows 10, AMD Radeon RX 480 4 GB RAM, 16 gb ram, Intel CPU 4 cores.

### Issue description


When switching to mobile render from forward + The alpha texture on the tree mesh starts to flicker.
Made a video: https://www.youtube.com/watch?v=WdGVi1hdRHo



### Steps to reproduce

Switching to mobile render from forward +

### Minimal reproduction project

Uploaded the project in google link: https://drive.google.com/file/d/1efEV914CWkyWoGzkv3RBMnw9t-4BVTeQ/view?usp=sharing
(only deleted the .godot - i guess its not needed.)
sorted_active_viewports_dirty = false;
	}
	HashMap<DisplayServer::WindowID, Vector<BlitToScreen>> blit_to_screen_list;
	
	RENDER_TIMESTAMP("> Render Viewports");
	
	draw_viewports_pass++;
	for (int i = sorted_active_viewports.size() - 1; i >= 0; i--) { 
		Viewport *vp = sorted_active_viewports[i];
		if (vp->update_mode == RS::VIEWPORT_UPDATE_DISABLED) {
			continue;
		}
		if (!vp->render_target.is_valid()) {
			continue;
		}
		
		bool visible = vp->viewport_to_screen_rect != Rect2();
		if (vp->use_xr) {
			if (xr_interface.is_valid()) {
				
				visible = true;
				
				Size2 xr_size = xr_interface->get_render_target_size();
				_viewport_set_size(vp, xr_size.width, xr_size.height, xr_interface->get_view_count());
			} else {
				
				visible = false;
				vp->size = Size2();
			}
		} else {