UploadWizard does not handle mirrored EXIF rotations when displaying thumbnails. In the screenshot below, all images should look the same; however, only 1, 3, 6 and 8 are correct. (See T75602 for source.)

However, MediaWiki doesn't handle them correctly, either (T75602: Mirrored EXIF rotations are not applied to thumbnails), so this is actually correct behavior right now (as it reflects how the thumbnail will look after the files are uploaded). But if we ever fix that bug, we'll need to fix this one too.