I created a simple reproducer (conceptually based on work from Klaus). I directly create the ObjectUrl from the file and it seems to work as expected. Below you will find the xpi and the mp3 I used for the test. Klaus, can you check if this works for you?
Bug 1872401 Comment 1 Edit History
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I created a simple reproducer add-on (conceptually based on work from Klaus). I directly create the ObjectUrl from the file and it seems to work as expected. Below you will find the xpi and the mp3 I used for the test. Klaus, can you check if this works for you?