: The original release may have had audio that lagged or led the video.

: The first version might have been incomplete, missing scenes, or ending prematurely.

: Issues with the codec settings (like AAC audio or H.264 video) that caused playback errors on standard devices. Key Features of Your File

Common reasons for a release to be updated with a "PROPER" tag include:

: The file could have suffered from frame drops, pixelation, or broken metadata.

Based on the filename, your specific file has these characteristics: MakeMKV No Longer Writes Metadata