I think the most likely scenario is that large orders are being prioritized over small ones.
Yifu stated in newsletter that the chip orders will be shipped in order of ordering in the shop. But even when he ships in order of order size... there are no more happy customers yet. There are many days in between now already.
They also said the miners will be shipped per pre-order sequence.
Then what we got now? Were batch#2 and batch#3 miners shipped per pre-order sequence?