### 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.)
if (vp->update_mode == RS::VIEWPORT_UPDATE_ALWAYS || vp->update_mode == RS::VIEWPORT_UPDATE_ONCE) {
				visible = true;
			}
			if (vp->update_mode == RS::VIEWPORT_UPDATE_WHEN_VISIBLE && RSG::texture_storage->render_target_was_used(vp->render_target)) {
				visible = true;
			}
			if (vp->update_mode == RS::VIEWPORT_UPDATE_WHEN_PARENT_VISIBLE) {
				Viewport *parent = viewport_owner.get_or_null(vp->parent);
				if (parent && parent->last_pass == draw_viewports_pass) {
					visible = true;
				}
			}
		}
		visible = visible && vp->size.x > 1 && vp->size.y > 1;
		if (visible) {
			vp->last_pass = draw_viewports_pass;
		}
	}
	int vertices_drawn = 0;
	int objects_drawn = 0;
	int draw_calls_used = 0;
	for (int i = 0; i < sorted_active_viewports.size(); i++) {
		Viewport *vp = sorted_active_viewports[i];
		if (vp->last_pass != draw_viewports_pass) {
			continue; 
		}
		RENDER_TIMESTAMP("> Render Viewport " + itos(i));
		RSG::texture_storage->render_target_set_as_unused(vp->render_target);
		if (vp->use_xr && xr_interface.is_valid()) {