My first thought was that it’s shocking to see an announcement like this on a Sunday. Then I realized they might be hoping the news gets buried. But with the election on Tuesday, I think that would have happened either way!
When companies want to bury the news, they release it on Friday. It's called "taking out the trash."
/Former journo
More likely these are new developments and Apple just heard of them relatively recently, keeping in mind that it's already Monday morning in China.
This is also quite likely retaliation from China for Biden's latest trade war actions. Apple, is after all, one of two major US companies whose share price has not been turned into rubble. Doing this days before Midterms, knowing how desperate the Democrats are, is perfect timing. If Apple's share price falls drastically, it will be headline news and will likely also materially impact most indexes.
What's the other major US company whose share price hasn't been rubble-ized? Why Tesla of course. And their biggest and - most likely - only profitable factory is in China.