This usually happens because image orientation can be handled in two different ways:

1. The pixels are physically rotated and saved in the correct direction.
2. The image file keeps the pixels as-is and stores orientation metadata telling software how to display it.

Phones commonly use metadata rather than rewriting the image data. Programs that read and honor that metadata will show the photo correctly. Programs that ignore it may show the image sideways or rotate thumbnails differently.

That’s why the same file can appear correct in one app, wrong in another, and even have mismatched thumbnails versus full-image views.

When you manually rotate and save in an editor, the result depends on whether that editor actually rotates the pixels, updates/removes the orientation metadata, or both. If the metadata and pixel data no longer agree, different programs may display different orientations.

To avoid this, use software that can permanently apply the rotation to the image data and save it so the pixels themselves are in the intended orientation.