Yes — in Apple Photos the manually edited date/time is not written back into the image or video file. It’s stored separately in the Photos library database, which is why tools like Immich usually fall back to the original capture date in EXIF / QuickTime metadata.

Photos Backup Anywhere does handle this case: it reads the adjusted date from the Photos library and stores that modified timestamp in its own SQLite database, linked to the backed-up file, so the edited date isn’t lost even though the file itself isn’t rewritten.