### Godot version

4.1.1 stable

### System information

Windows 10

### Issue description

this is the default size loaded on startup 1024 which seems fine but it actually have loaded the default [2048] and ignored the size in project settings
![image](https://github.com/godotengine/godot/assets/53877170/c8c71de7-468a-487f-8e6c-dba1ce0f8fa5)

changing it now to any size will break it 
[2048]
![image](https://github.com/godotengine/godot/assets/53877170/3082ff09-b7d7-41f7-8fbb-813074a54135)

[512]
![image](https://github.com/godotengine/godot/assets/53877170/5ea4620f-52b5-4d0e-a5f5-747e777cd59d)


### Steps to reproduce

change 2d shadow atlas size in project settings while using compatibility renderer. 

### Minimal reproduction project

_
}
			_render_items(p_to_render_target, item_count, canvas_transform_inverse, p_light_list, r_sdf_used, true);
			item_count = 0;
			if (ci->canvas_group->blur_mipmaps) {
				texture_storage->render_target_gen_back_buffer_mipmaps(p_to_render_target, ci->global_rect_cache);
			}
			canvas_group_owner = nullptr;
			
			backbuffer_cleared = false;
			
			ci->use_canvas_group = true;
		} else {
			ci->use_canvas_group = false;
		}
		if (backbuffer_copy) {
			if (update_skeletons) {
				mesh_storage->update_mesh_instances();
				update_skeletons = false;
			}
			
			_render_items(p_to_render_target, item_count, canvas_transform_inverse, p_light_list, r_sdf_used);
			item_count = 0;
			texture_storage->render_target_copy_to_back_buffer(p_to_render_target, back_buffer_rect, backbuffer_gen_mipmaps);
			backbuffer_copy = false;
			material_screen_texture_cached = true; 
			material_screen_texture_mipmaps_cached = backbuffer_gen_mipmaps;
			backbuffer_gen_mipmaps = false;
		}
		if (backbuffer_gen_mipmaps) {
			texture_storage->render_target_gen_back_buffer_mipmaps(p_to_render_target, back_buffer_rect);