### 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_V(!viewport, 0);
	return double(viewport->time_cpu_end - viewport->time_cpu_begin) / 1000.0;
}
float RendererViewport::viewport_get_measured_render_time_gpu(RID p_viewport) const {
	Viewport *viewport = viewport_owner.get_or_null(p_viewport);
	ERR_FAIL_COND_V(!viewport, 0);
	return double((viewport->time_gpu_end - viewport->time_gpu_begin) / 1000) / 1000.0;
}
void RendererViewport::viewport_set_snap_2d_transforms_to_pixel(RID p_viewport, bool p_enabled) {
	Viewport *viewport = viewport_owner.get_or_null(p_viewport);
	ERR_FAIL_COND(!viewport);
	viewport->snap_2d_transforms_to_pixel = p_enabled;
}
void RendererViewport::viewport_set_snap_2d_vertices_to_pixel(RID p_viewport, bool p_enabled) {
	Viewport *viewport = viewport_owner.get_or_null(p_viewport);
	ERR_FAIL_COND(!viewport);
	viewport->snap_2d_vertices_to_pixel = p_enabled;
}
void RendererViewport::viewport_set_default_canvas_item_texture_filter(RID p_viewport, RS::CanvasItemTextureFilter p_filter) {
	ERR_FAIL_COND_MSG(p_filter == RS::CANVAS_ITEM_TEXTURE_FILTER_DEFAULT, "Viewport does not accept DEFAULT as texture filter (it's the topmost choice already).)");
	Viewport *viewport = viewport_owner.get_or_null(p_viewport);
	ERR_FAIL_COND(!viewport);
	viewport->texture_filter = p_filter;
}
void RendererViewport::viewport_set_default_canvas_item_texture_repeat(RID p_viewport, RS::CanvasItemTextureRepeat p_repeat) {