Regardless of the consumer product, everything about getting product from production to the consumer has gone up in price....Mostly due to how people are shopping online for EVERYTHING now versus just some things before Covid.
  1. Labor shortages abound are causing wages to go up hitting raw materials production.
  2. Prices for containers has gone up across the world as the major online company goods are using more of them.
  3. Prices for shipping containers has gone up as space on container ships is at a premium.
  4. Paper shortages are causing the price of boxes to go up for shipping product.

Then of course regular gun owner annual/biannual/election panic causing additional buying over normal stressing the supply/demand even more.

I would imagine ammo manufacturers are only willing to add so much capacity with capital investment into infrastructure. When 9mm is $105/1000 it doesn't make sense anymore, but $599/1000 it does. That 6X spread is nice until it goes down with gluts piling up as buying levels off.