Nor is it in mine. I was only suggesting how, in the past, I’d had correctly dated/timed files without the phone attached. Normally I fly with a dedicated drone-phone.
Since you bought the second-hand P3, have any of the photos/videos been correctly dated?
If not, then there’s always a possibility that there’s an issue with the P3.
If some have been correctly time stamped, then I think this is unlikely.
So - what we have determined is that the system date on a DJI drone is set from the attached tablet/phone.
So - were I you - I’d do the following to try and identify the cause of the problem …
1 - If you have another phone/tablet - try this. (You don’t even have to fly - you can just switch everything on in the house and take a photo - as I did last evening for the above test.)
2 - Try using a new(different) USB cable between controller and tablet.
3 - Uninstall the software on your tablet and then reinstall.