Why Did My Google Takeout Download Link Expire?
Takeout links last about a week and allow only a few download attempts. Here is how to get your export back and how to avoid losing it again.
Google Takeout links are deliberately short-lived. You get roughly a week, and only a handful of download attempts per archive. A failed download often burns an attempt, so a flaky connection can use them up faster than you expect.
If yours has expired, you cannot renew it. Request a new export. Two things make the second attempt go better: choose a smaller archive size, such as 2 GB or 10 GB instead of 50 GB, so a failed part costs you minutes rather than hours; and have Takeout deliver to Google Drive, OneDrive or Dropbox instead of your browser, which removes the download timeout entirely. Then pull the files down from there at your own pace.
While you wait, do not delete anything from Google Photos. The export is not a backup until it is complete and verified on your disk.
When the new export lands, remember that the photos arrive without their dates inside them. That is the next problem, and it is the easy one. The app reads every .json sidecar across all the zip parts and writes the real capture date and GPS into each photo, so what you keep is a library that reads correctly anywhere. The first 500 photos are free.