What audio device are you using? I got this issue playing it as well and resolved it by using the stock audio instead.
I usually only get this issue in Godot 4.x web export games (maybe it's fixed in the very latest stable 4.3 Godot, but not 100% sure about that).
This game is made in Unity though, so it's very odd the issue is in this game. I am really curious what may be causing this issue, especially in a Unity web export.
Does it depend on the version of Unity used to develop the game? I'm not 100% sure what may cause it but I'm curious.