I bought my AirPods Pro second generation directly from Apple, A3047 under one airpod and A3048 under the other. on my phone it says A3048. why?

This explains.

Identify your AirPods - Apple Support

There are separate model numbers for the AirPods case, left AirPod and right AirPod. Presumably you’re specifying left or right one way or another.

So this doesn’t answer the question as to why the model number on the physical AirPod is different than the model number found in the settings. For me the physical AirPod says (A3047) the settings says the model number is (A3048) I want to replace a single lost AirPod Pro and need to know which model number to go with if the difference even matters.