Thank you! The effect itself is a simple fullscreen shader on a color rect (I modified a shader I found on the godot shaders site, you can find a lot here: https://godotshaders.com/shader-tag/transition) - I attached a script to it to tween its shader parameters (how much of the screen is covered, and from which direction to transition). This color rect scene is spawned in by the SceneManager (autoload) whenever I reload or go to a new scene - so its independent of the levels itself.