How Do I Move Google Photos to Another Google Account Without Losing Metadata?
Copying a Takeout export into a second Google account loses your dates. Google ignores the .json files on upload. Here is what to do first.
This one surprises people, because it feels like it should just work. It does not.
If you download a Takeout export and upload it to a second account, Google Photos reads the EXIF inside each file and ignores the .json sidecars completely. They are its own files, in its own format, and it will not read them back. So every photo that had no EXIF date arrives in the new account dated today, and your carefully ordered library lands as one enormous pile. Then you are stuck, because now the dates are wrong on Google's side too.
Google does offer a direct account-to-account transfer, which keeps the metadata because nothing leaves Google. Try that first. It has limits on shared albums and it does not move everything, so check the count on both sides.
If you go the manual route, fix the files before you upload. The app writes the real date and location into each photo, so what you upload already carries its own metadata and the new account reads it correctly. This is the one step that decides whether the migration works. The first 500 photos are free, so test with an album you can verify.