Why Does My Phone Show a Different Date From My Computer?
They are reading different fields. The phone reads the photo, the computer often reads the file.
Phone galleries read the date inside the photo, and often keep their own database of it. File managers on a computer show the file's dates by default, which change whenever the file is copied.
So the phone can be right and the computer wrong about the same photo, at the same time, with neither of them lying.
Write the real date into the photo and onto the file and they agree. Takeout JSON Metadata Fixer does both. It runs on your own computer and is free for your first 500 photos.