I just can’t understand why companies do this weird shit, I always thought order earlier = arrive faster, this is just… weird)

My guess is you’re seeing a tiny view of a global logistics company at work. There are warehouses all over the place and there is large overlap with the inventory in each. Lets say you’re ordering a hot pink Kindle ebook reader. If you were able to see from the Amazon side, you’d see this item represented in dozens of warehouses all over the world. There is possibly one sitting on the shelf in the warehouse right down the street from you, which would ship it to you the fastest. However, that warehouse also contains other inventory that is in high demand and that other inventory is NOT in other warehouses. So the Amazon algorithms don’t want to direct fulfillment of your order from this close warehouse to you because its getting crushed right now.

Instead it finds the hot pink Kindle in a slow warehouse much farther away from you and your order is fulfilled from there (your first order with the long shipping time). Later, the close warehouse runs out of the high-demand inventory that was keeping it busy. You make second order for the hot pink Kindle and the algorithm now optimizes for cheapest/fastest delivery, which is the warehouse down the street from you (your second order).

Welcome to global logistics.