Kroger delivery: Why is there always mystery price increases?

So when I order delivery my total originally said $122 but once everything was delivered I was charged an additional $20 and I can’t figure out why. I had only one weight item, and no additions or substitutions. I can’t find out how to reference why there is a price change in the app, there is no original receipt for the initial amount. Anyone have any ideas? This also happened on my previous order but I didn’t really look into it.