This is recent behavior and not a function of order preferences. I have placed three orders that were grouped together (send order as one shipment) despite having selected the earlier Prime delivery option. This started on the same day that I received an order that was broken up (ship as available), which is what usually happens with Prime Pantry orders to my address.
In other words, my Prime orders make me think that Amazon is experiencing a massive ordering surge, and is grouping items together in an atypical way because they want to reduce the shipping strain.
People are starting to get just a little nuts on these things... Shouldn't need to stock up months of stuff... a few weeks of food and water with some rice and beans and/or lentils and lard as backup staple items for core items with other canned goods.
I, personally, cannot handle legumes and not really a fan of grains... that said, having enough hand sanitizer for a year is a bit nuts. Having more food than you will cycle through in a regular time-frame will only serve to add undue pressure to short term supplies because of over-stocking up... then the relief may not come, or can kill the other end of the line, or increase tainted supply.
Panic just isn't a good idea.
Like I said in the item text, the product category in question is completely sold out (except for questionable, expensive imports) and won't be in-stock for another week or two, which will be firmly inside the pandemic acceleration period. Instead, I went with several cases of UHT milk in 8 oz containers that were good and cheap. Powdered milk has the added costs of desiccation, whereas UHT is more/less fancy pasteurization.
"Powered milk" sounds like some kind of bodybuilder beverage that contains no actual milk.
PS: It's either "Beefcake. Beefcake! Weight Gain 4000!" or Impossible Milk.
Even then, the shortage will likely be short-lived as preppers stock up and stop buying more.
So...?