You posted the PGN file of a chess game and its metadata. The file content looks fine.
In the source code of the HTML viewer, find an element for the image of any chess piece. If the image is encoded in base64, copy and paste the whole element into the source of a new HTML document. If it contains a URL pointing at an external asset, launch the URL.
If you can’t see the chess piece this way, it’s likely the images for chess pieces are corrupted.