There does seem to be an issue with the web version where the note spawn will shift downward the longer the song goes so you get no time.
In some of the longer songs, the notes end up spawn off the screen.
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Yeah sorry about that, it's a glitch caused by too much lag. Make sure graphics acceleration is on in your browser's settings. If you're using Firefox, try a Chrome (or another Chromium based browser), as Firefox has issues with Godot web games unfortunately. If that doesn't fix it, the downloadable version should have better performance, making this less likely