Yet again twitter cards were causing me pain. This time it was me not realizing that they require full urls, and not relative or abolute urls.
This was not working
<meta name="twitter:image" content="/shot/?path={{ request.url|quote_plus }}" content-type='image/png'/>
This does work with a full url
<meta name="twitter:image" content="https://thoughts.waylonwalker.com/shot/?path={{ request.url|quote_plus }}" content-type='image/png'/>