I was almost convinced they were keeping this broken on purpose, it's been broken so long. Like, years long.
It was broken so long I honestly wouldn't have been surprised if news surfaced that Discord was taking back-handers from Microsoft under the table to keep it broken. With steam working so well on Linux now, broken discord streaming without actual working audio share was one of the last things that posed a hurdle for gamers ditching Windows.
(In the meantime, thank you Vesktop for your service <3)