This has happen before. If we remember correctly, it had to do with shipping where there was an adjustment. We had it happen once where Amazon Buy Shipping was charging $7.60 for USPS Priority Mail Flat Rate Envelope. When Amazon set up their system, they failed to realize this USPS special rate did not apply to destinations outside of the continental 48 states which meant that Hawaii and Alaska were not included in that price. Those two states were to remain at $8.05. This made us have an “other” charge with no explanation.
Here is the post we created on it in August of 2023
Other Charge with no Explaination
Eventually, we got a Mod to look into it on NSFE and the response came back to us in a case created by the Mod. Since this was an Amazon faulted error, we were suppose to get the charge returned to us. That never happened.
Some how Amazon received a charge from one of your shippers about one or more of your shipments where there was a price difference. If you are not talking a lot of money (ours was only $1.35), it is probably not worth your time to dig into it further.