It was because they announced they were speeding up their plans for their affordable next gen vehicle earlier than already announced, which was H2 2025
Now it's late 2024/H1 2025
They are ditching their next gen "unboxed" production method to do this however and leaving that for the robo taxi. The vehicles will be a hybrid if their next gen tech and existing tech. They claim the new models to be released will be built on the existing manufacturing lines, getting them to over 3mil vehicles a year.
These will be more akin to a gen 2.5.
Robo taxi will be gen 3
If their unboxed plans work with the taxi, they'll use it for other vehicles in the future.
Edit: they basically derisked the cheaper vehicles by foregoing the risky new production method that would make it cheaper in the long run, by figuring out how to use their existing lines, also making it cheaper. But in the grand scheme of things i imagine this hybrid way will have less margins than a successfully implemented new way.
Also, some of the price crash was from Reuters reporting they abandoned the cheaper vehicle in favor of robotaxi and there's been uncertainty for weeks now ok the topic, until now.