A PDF is a container.
A shared link is pulling the wrong title, description or image and you need to inspect the page metadata.
Website & SEO
Check what your link says when it gets shared.
Inspect Open Graph and Twitter/X tags and preview the title, description and image exposed by a public page.
Useful to know
Four things worth knowing.
Opening is not the same as correct.
Social apps cache link previews, so fixing the source does not always refresh every platform immediately.
Check the changed pages.
Confirm the source Open Graph values are correct before blaming an old cached card.
Keep the source document.
Fix the metadata first; then use the platform's refresh/debug workflow if an old preview persists.