This theory seems to be correct. A keystroke after the URL fetches the card. This key cannot be a letter (would mess up URL) or a point. Space is fine. Rest not tested.
Reposted from
Kilian Valkhof
Here's my theory: all your posts end with cssday.nl but Bluesky only starts fetching the data after a next keypress (space) so it never started fetching the preview for you.
Comments
Until that point you might still be adding to the url to go to (e.g. https://cssday.nl/speakers.html)