This appears to be a related bug on the Godot issue tracker:
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“SharedArrayBuffer does not work with Firefox on Android anymore #86988”: https://github.com/godotengine/godot/issues/86988
“A few days ago [issue created 9 Jan 2024] my Godot game stopped working on Itch.IO when opened from a Firefox Android app. […]”
From other comments on the issue it seems like it might be Release and Beta versions default to an error on expiry.