Rear camera changed output from 3u tools software

I am using an iphone xs which I bought recently from my friend. Everything is up to the mark but 3u tools report is showing 'rear camera changed' as the serial number of factory and attached camera is different. I am confused because there is no such notification of service or replaced parts in the phone, It is water pack, no minor difference in the picture quality however it is dropping the focus. Let me know should I go for replacement or should keep it ?