The Xiaomi 10400mAh is EOL, has been for over a year.
The Xiaomi 10000mAh (18650-based) is about to be EOL, that's why the price have been steadily going up the last few months.
It's being replaced with a LiPo based 10000mAh, called powerbank 2. User will34 wrote an excellent review about it. Yes, it's a little more expensive than the 18650-based model it is replacing, but it also perfoms a lot better. They basically took the 10.000mAh Mi Pro (with usb-c) and gave it micro-usb instead.
I also have one for testing, but as I am battling legionnaire's disease right now, testing will have to wait.