Earlier quoted context omitted.
$7,386 seems to be roughly one Cybertruck batteries worth (the only vehicle that uses that battery). As in they literally expect to build one more Cybertruck battery and that's it. I'm guessing the excess stock in the Tesla factories covers spares for a few years already. I wonder when the cancellation will be announced by Tesla? It's all but leaked at this point.
Maybe they did this to keep the contract with a symbolic value; or to avoid the headlines that Tesla 'cancelled' the contract? A '99% write down' is such an uncommon term that many people might not register it.
Tax reasons? Keep it on the book and write the loss off against other profit over coming years? No clue how it would work in practice but it sounds taxy.