YouTube Shorts look different in the app, but their public links still resolve to a normal video ID. That means the thumbnail workflow is almost identical to a regular YouTube video: copy the Shorts link, test the known image sizes, and save the best available result.
Copy the Shorts URL
Use the Share button or copy the URL from your browser. A Shorts URL usually looks like youtube.com/shorts followed by the video ID.
Paste that full link into the downloader. You do not need to manually convert it into a watch URL first.
Expect the same thumbnail sizes
Shorts can expose maxresdefault, sddefault, hqdefault, mqdefault, or only the small default image. The vertical format of the video does not guarantee a vertical public thumbnail file.
If the preview looks cropped, that may be the public image YouTube exposes for the Short rather than a downloader problem.
Troubleshoot missing Shorts thumbnails
If no sizes load, make sure the Short is public and the copied link contains the actual video ID. A channel link, playlist link, or copied app route may not be enough.
Try opening the Shorts link in a browser. If the browser cannot resolve it cleanly, fix the link before testing thumbnail downloads again.