Bug: The music's volume is controlled by the window's size. At 1440P, it's inaudible even with the in-game slider maxed out, but it gets increasingly louder as the window is scaled down.
It looks like your AudioStreamPlayer2D node is set to fade out as it approaches 2000 pixels from wherever the listener is. Using an AudioStreamPlayer node instead seems like it'd fix that
(I'm not super familiar with Godot, but it seems like the listener is defaulting to being located (0,0), so just putting the node there might also work?)