Invoice date changed

We are trying to figure out how a date on an invoice changed.     A customer shipment was done in Nov 2022.     For some reason a copy of the order and pack slip with shipping info didn’t get to accounting until early January, and a invoice was created in January for the shipment.    a week later looking at the invoice it says the invoice date was 11/7/2022, which is when the shipment actually happened.   Why would the date on the invoice change?   Wondering if the functionality of invoice causes this, or if it is a bug or if someone would have to manually change it for this to happen.   Just wondering if anyone else has seen this happen and can explain why or how it happens.