### 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.)
Viewport *viewport = viewport_owner.get_or_null(p_viewport);
	ERR_FAIL_COND(!viewport);
	viewport->texture_mipmap_bias = p_mipmap_bias;
	if (viewport->render_buffers.is_valid()) {
		viewport->render_buffers->set_texture_mipmap_bias(p_mipmap_bias);
	}
}
void RendererViewport::viewport_set_scaling_3d_scale(RID p_viewport, float p_scaling_3d_scale) {
	Viewport *viewport = viewport_owner.get_or_null(p_viewport);
	ERR_FAIL_COND(!viewport);
	
	
	
	if (viewport->scaling_3d_scale == CLAMP(p_scaling_3d_scale, 0.1, 2.0)) {
		return;
	}
	viewport->scaling_3d_scale = CLAMP(p_scaling_3d_scale, 0.1, 2.0);
	_configure_3d_render_buffers(viewport);
}
void RendererViewport::viewport_set_size(RID p_viewport, int p_width, int p_height) {
	ERR_FAIL_COND(p_width < 0 && p_height < 0);
	Viewport *viewport = viewport_owner.get_or_null(p_viewport);
	ERR_FAIL_COND(!viewport);
	ERR_FAIL_COND_MSG(viewport->use_xr, "Cannot set viewport size when using XR");
	_viewport_set_size(viewport, p_width, p_height, 1);
}
void RendererViewport::_viewport_set_size(Viewport *p_viewport, int p_width, int p_height, uint32_t p_view_count) {