The only reason these audio-focused projects were started was that at the start of 2021 people believed it was a "Mark priority", and everyone wanted to ship something by the end of H1 2021 so it would make it into their performance reviews. (This is also the explanation for why so many companies including Twitter, FB and Spotify shipped audio products around May-June 2021. Everybody ran on the same review cycle.)
It's hard to exaggerate how much of FB's flailing is explained by internal beliefs in something being a Mark priority, which then shifts to something else by the next half. It's a downside of being a founder-owned company at this scale – the signals from the top become caricatures of "Great Leader probably wants X now."