Link posts from thetyee.ca appear to be previewing the Cloudflare captcha challenge “Attention Required! | Cloudflare” prompt instead of actual content.
What it looks like (two examples - this seems to be a consistent problem for thetyee):
(from https://lemmy.ca/post/39053782)
(from https://lemmy.ca/post/39058782)
What it should look like (a different post):
My guess is that the rich link preview is generated in Lemmy’s backend, and Cloudflare thinks that the IP address of lemmy.ca’s host is full of bots.
No educated guess on the solution, though, but I’d guess that other Lemmy admins have seen sort of thing too.
The preview generator is an “automated” visit of the page so the site tends to reject it.
Usually, OPs put a short summary of their own in the post body text, plus their thoughts in a top-level comment.